I created a multibranch job with several branches for some testing. When I reached 30 branches, the Gitea plugin stopped adding new branches to the multibranch job. I switched to GitHub branch source plugin and it was able to continue adding branches.

I searched for a Gitea branch scanning limit and did not find one in the Gitea configuration. However, I'm an inexperienced Gitea administrator and may have missed something in the configuration settings.