Hi
I had exactly the same issue.
The strange thing is that we already merged the internal master with the 2.54.0 release in January. That was a normal merge with some minor conflicts and roughly 300 commits.
Then I wanted to upgrade to 2.55.3 and I also got many conflicts and around 12.000 commits from 2017 even.
So, can it be that somehow the git history status was changed and now the local version can not be easily compared to the remote version?