I think it is possible to optimize the assembly of docker containers. Currently, the firebird installer is loaded by the ADD command into each container separately, while creating a layer in them that is not needed when using, but increases the volume of containers.
Maybe it would be better like this:

$ mkdir <path for all>/tmp
$ wget -O tmp/firebird-bundle.tar.gz https://github.com/FirebirdSQL/firebird/releases/download/v5.0.1/Firebird-5.0.1.1469-0-linux-x64.tar.gz

And exclude ADD in the dockerfiles, using instead:
RUN --mount=type=bind,from=<path for all>/tmp,dst=/tmp,rw set -eux; cd /tmp; tar --extract ...
You won't need to download the installer for each tag and the size of the containers will decrease.