I would imagine that the creation of the 5.0 branch is an indicator that this is the branch with which to target for compatibility with the official 5.0 release, and that continuing to work off of ue5-main opens you up to getting ahead of the release schedule and incompatible with the official 5.0 release. Probably is already the case even, since ue5-main is already bumped to 5.1
Is that accurate @VictorLerp ?