1. Gitea, Inc replaced the prior community leadership structure with one controlled by Gitea, Inc and have pivoted into being primarily about a hosted code SaaS they launched this year that didn't exist for the first 7 years of the project. They could do it because they had 2 of the 3 seats on the community stewardship organisation at the time to vote for it, but that wasn't always true. For a lot of people, Gitea's primary motivation was for the self-hosted and fully open use case, but now it's not clear that that will remain any more of a priority for Gitea Inc as it is for e.g. Gitlab

2. There were also some contributors who were interested for the sake of decentralising code forges (and not just git), and so were big into the forgefed project which was an activitypub based federation protocol. Gitea Inc were officially on board with that, but the contributors felt they weren't helpful enough to actually implementing that with missteps like letting grant funding from NLNet expire.

The contributors from groups 1 and 2, and Codeberg banded together to make Forgejo after the Gitea change.

Until the latest release (just last month) Forgejo was one way pulling all changes from Gitea, but they've diverged enough that they're now hard forks. Both have active development, but Forgejo's main unique focus is the federation stuff, while Gitea's was enhancing their CI offering. But while Gitea may have more development effort, being funded by a commercial organisation rather than volunteers and a non-profit, I think they have a long way to catch up to Gitlab in that front, so it feels like they've dropped their unique factor to try chase Gitlab.