I'm not sure either, the forgejo/gitea fork seems to also involve a lot of activism and interpersonal drama. And codeberg shares a lot of the people involved in that drama on the forgejo side. The gitea/opencollective side has it's own share of "difficult" people.

So I know of no technical reason why any should be better. And the potential for drama and conflict inherent in the developers of both projects make me wary. In the end I decided to use forgejo, because absent a corporation at least the possibility of a corporate rugpull is reduced.