It’s actually not behind at all, it’s just that github doesn’t count squashed commits in case. Basically the commit ( merges the latest engine changes for 4.21 so you should be good to go. The reason I squash commits like is because if I just did a regular merges without squashing, it would spam the commit list with those changes instead so people wouldn’t know what actual changes the repo does (as the relevant commits would be mixed with the stream of other random commits).
I recently redid all my physics branches so that I used only latest versions as base directly, for example and the mentioned are both in sync with 4.21.2 but github only reports the latter to be behind 