You say "one of the larger contributors upstream" do you have a source for that? Because I took a look at the contributor list, and couldn't find any evidence of that.
Codeberg maintain their own long-standing fork of Gitea and have members that are also maintainer at the Gitea project. It is the persons doing upstream contributions, not a Codeberg account.
Their fork lives here: https://codeberg.org/Codeberg/gitea