I just upgraded zabbix-agent2 from bullseye-backports, and found that all the pgsql items became unsupported.
I don't know if you noticed, but it turns out upstream thought it was a good idea to remove the built-in
PostgreSQL support and put it in a separate plugin with its own repository
(https://git.zabbix.com/projects/AP/repos/postgresql/browse) on a stable branch.

Since zabbix-agent2 didn't become part of an official Debian release until after this regression happened,
I suppose this should probably rather be a wishlist bug against wnpp, but I thought I'd let you know in
this manner. I could package the plugin if you like.

Ooooh, I looked closer at this now and realised that there are a number of
dependencies that also need to be packaged, because we can't have go build
downloading modules over the Internet. For starters, https://git.zabbix.com/
projects/AP/repos/plugin-support, which in turn declares a dependency on
github.com/Microsoft/go-winio, but I think that's only for Windows. The plugin
itself also requires github.com/omeid/go-yarn, but I think that's all that's
missing.