firebird3.0-server binary package in Ubuntu Focal amd64

 Firebird is a relational database offering many ANSI SQL-99 features that
 runs on Linux, Windows, and a variety of Unix platforms. Firebird offers
 excellent concurrency, high performance, and powerful language support
 for stored procedures and triggers. It has been used on production systems
 under a variety of names since 1981.
 .
 This package contains the server binary as well as its configuration files.
 The default mode of operation is the so called "super", which is a
 single-threaded server process with shared database cache between
 connections. The two other operation modes -- "classic" (separate
 process/cache for each connection) and "superclassic" (separate thread/cache
 for each connection) are also available via configuration options.

Source package