With kernel 5.0.0-11-generic and nouveau, Ubuntu MATE has wrong colors and can't control brightness

With the latest kernel (5.0.0-11-generic) my MacBook with nouveau shows wrong colors and can't control brightness while running Ubuntu MATE. For example, Ubuntu MATE green appears as teal and orange like in the Firefox logo and window decorations is blue. This includes the plymouth boot logo, but not the desktop wallpaper.

Screen brightness can't be controlled at all, neither with the keyboard keys (which have always worked automatically) nor in the Control Center > Power Management because no brightness slider appears at all.

This also occurs in a live session from the latest daily build (20190413.3).

It does NOT occur in a live session of the latest (20190413.2) Ubuntu Desktop (GNOME).

By editing /etc/default/grub to boot the previous kernel (5.0.0-8-generic), it works normally again.
---
ProblemType: Bug
ApportVersion: 2.20.10-0ubuntu27
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: ubuntu-mate 1784 F.... pulseaudio
CasperVersion: 1.403
CurrentDesktop: MATE
DistroRelease: Ubuntu 19.04
IwConfig:
 lo no wireless extensions.

 enp0s10 no wireless extensions.
LiveMediaBuild: Ubuntu-MATE 19.04 "Disco Dingo" - Alpha amd64 (20190413.3)
MachineType: Apple Inc. MacBook5,1
Package: linux (not installed)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=C.UTF-8
 SHELL=/bin/bash
ProcFB: 0 EFI VGA
ProcKernelCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/username.seed boot=casper quiet splash ---
ProcVersionSignature: Ubuntu 5.0.0-11.12-generic 5.0.6
RelatedPackageVersions:
 linux-restricted-modules-5.0.0-11-generic N/A
 linux-backports-modules-5.0.0-11-generic N/A
 linux-firmware 1.178
RfKill:
 0: hci0: Bluetooth
  Soft blocked: no
  Hard blocked: no
Tags: disco
Uname: Linux 5.0.0-11-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
_MarkForUpload: True
dmi.bios.date: 04/27/09
dmi.bios.vendor: Apple Inc.
dmi.bios.version: MB51.88Z.007D.B03.0904271443
dmi.board.asset.tag: Base Board Asset Tag#
dmi.board.name: Mac-F42D89C8
dmi.board.vendor: Apple Inc.
dmi.board.version: Proto
dmi.chassis.asset.tag: Asset Tag#
dmi.chassis.type: 10
dmi.chassis.vendor: Apple Inc.
dmi.chassis.version: Mac-F42D89C8
dmi.modalias: dmi:bvnAppleInc.:bvrMB51.88Z.007D.B03.0904271443:bd04/27/09:svnAppleInc.:pnMacBook5,1:pvr1.0:rvnAppleInc.:rnMac-F42D89C8:rvrProto:cvnAppleInc.:ct10:cvrMac-F42D89C8:
dmi.product.family: MacBook
dmi.product.name: MacBook5,1
dmi.product.sku: System SKU#
dmi.product.version: 1.0
dmi.sys.vendor: Apple Inc.
---
ProblemType: Bug
ApportVersion: 2.20.10-0ubuntu27
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: ubuntu-mate 1784 F.... pulseaudio
 /dev/snd/pcmC0D0p: ubuntu-mate 1784 F...m pulseaudio
CasperVersion: 1.403
CurrentDesktop: MATE
DistroRelease: Ubuntu 19.04
IwConfig:
 lo no wireless extensions.

 enp0s10 no wireless extensions.
LiveMediaBuild: Ubuntu-MATE 19.04 "Disco Dingo" - Alpha amd64 (20190413.3)
MachineType: Apple Inc. MacBook5,1
Package: linux (not installed)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=C.UTF-8
 SHELL=/bin/bash
ProcFB: 0 EFI VGA
ProcKernelCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/username.seed boot=casper quiet splash ---
ProcVersionSignature: Ubuntu 5.0.0-11.12-generic 5.0.6
RelatedPackageVersions:
 linux-restricted-modules-5.0.0-11-generic N/A
 linux-backports-modules-5.0.0-11-generic N/A
 linux-firmware 1.178
RfKill:
 0: hci0: Bluetooth
  Soft blocked: no
  Hard blocked: no
Tags: disco
Uname: Linux 5.0.0-11-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
_MarkForUpload: True
dmi.bios.date: 04/27/09
dmi.bios.vendor: Apple Inc.
dmi.bios.version: MB51.88Z.007D.B03.0904271443
dmi.board.asset.tag: Base Board Asset Tag#
dmi.board.name: Mac-F42D89C8
dmi.board.vendor: Apple Inc.
dmi.board.version: Proto
dmi.chassis.asset.tag: Asset Tag#
dmi.chassis.type: 10
dmi.chassis.vendor: Apple Inc.
dmi.chassis.version: Mac-F42D89C8
dmi.modalias: dmi:bvnAppleInc.:bvrMB51.88Z.007D.B03.0904271443:bd04/27/09:svnAppleInc.:pnMacBook5,1:pvr1.0:rvnAppleInc.:rnMac-F42D89C8:rvrProto:cvnAppleInc.:ct10:cvrMac-F42D89C8:
dmi.product.family: MacBook
dmi.product.name: MacBook5,1
dmi.product.sku: System SKU#
dmi.product.version: 1.0
dmi.sys.vendor: Apple Inc.
---
ProblemType: Bug
ApportVersion: 2.20.10-0ubuntu27
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: ubuntu-mate 1784 F.... pulseaudio
CasperVersion: 1.403
CurrentDesktop: MATE
DistroRelease: Ubuntu 19.04
IwConfig:
 lo no wireless extensions.

 enp0s10 no wireless extensions.
LiveMediaBuild: Ubuntu-MATE 19.04 "Disco Dingo" - Alpha amd64 (20190413.3)
MachineType: Apple Inc. MacBook5,1
Package: linux (not installed)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=C.UTF-8
 SHELL=/bin/bash
ProcFB: 0 EFI VGA
ProcKernelCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/username.seed boot=casper quiet splash ---
ProcVersionSignature: Ubuntu 5.0.0-11.12-generic 5.0.6
RelatedPackageVersions:
 linux-restricted-modules-5.0.0-11-generic N/A
 linux-backports-modules-5.0.0-11-generic N/A
 linux-firmware 1.178
RfKill:
 0: hci0: Bluetooth
  Soft blocked: no
  Hard blocked: no
Tags: disco
Uname: Linux 5.0.0-11-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
_MarkForUpload: True
dmi.bios.date: 04/27/09
dmi.bios.vendor: Apple Inc.
dmi.bios.version: MB51.88Z.007D.B03.0904271443
dmi.board.asset.tag: Base Board Asset Tag#
dmi.board.name: Mac-F42D89C8
dmi.board.vendor: Apple Inc.
dmi.board.version: Proto
dmi.chassis.asset.tag: Asset Tag#
dmi.chassis.type: 10
dmi.chassis.vendor: Apple Inc.
dmi.chassis.version: Mac-F42D89C8
dmi.modalias: dmi:bvnAppleInc.:bvrMB51.88Z.007D.B03.0904271443:bd04/27/09:svnAppleInc.:pnMacBook5,1:pvr1.0:rvnAppleInc.:rnMac-F42D89C8:rvrProto:cvnAppleInc.:ct10:cvrMac-F42D89C8:
dmi.product.family: MacBook
dmi.product.name: MacBook5,1
dmi.product.sku: System SKU#
dmi.product.version: 1.0
dmi.sys.vendor: Apple Inc.
---
ProblemType: Bug
ApportVersion: 2.20.10-0ubuntu27
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: ubuntu-mate 1784 F.... pulseaudio
CasperVersion: 1.403
CurrentDesktop: MATE
DistroRelease: Ubuntu 19.04
IwConfig:
 lo no wireless extensions.

 enp0s10 no wireless extensions.
LiveMediaBuild: Ubuntu-MATE 19.04 "Disco Dingo" - Alpha amd64 (20190413.3)
MachineType: Apple Inc. MacBook5,1
Package: linux (not installed)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=C.UTF-8
 SHELL=/bin/bash
ProcFB: 0 EFI VGA
ProcKernelCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/username.seed boot=casper quiet splash ---
ProcVersionSignature: Ubuntu 5.0.0-11.12-generic 5.0.6
RelatedPackageVersions:
 linux-restricted-modules-5.0.0-11-generic N/A
 linux-backports-modules-5.0.0-11-generic N/A
 linux-firmware 1.178
RfKill:
 0: hci0: Bluetooth
  Soft blocked: no
  Hard blocked: no
Tags: disco
Uname: Linux 5.0.0-11-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
_MarkForUpload: True
dmi.bios.date: 04/27/09
dmi.bios.vendor: Apple Inc.
dmi.bios.version: MB51.88Z.007D.B03.0904271443
dmi.board.asset.tag: Base Board Asset Tag#
dmi.board.name: Mac-F42D89C8
dmi.board.vendor: Apple Inc.
dmi.board.version: Proto
dmi.chassis.asset.tag: Asset Tag#
dmi.chassis.type: 10
dmi.chassis.vendor: Apple Inc.
dmi.chassis.version: Mac-F42D89C8
dmi.modalias: dmi:bvnAppleInc.:bvrMB51.88Z.007D.B03.0904271443:bd04/27/09:svnAppleInc.:pnMacBook5,1:pvr1.0:rvnAppleInc.:rnMac-F42D89C8:rvrProto:cvnAppleInc.:ct10:cvrMac-F42D89C8:
dmi.product.family: MacBook
dmi.product.name: MacBook5,1
dmi.product.sku: System SKU#
dmi.product.version: 1.0
dmi.sys.vendor: Apple Inc.