OTOH the PolarDB specific changes seem to be contained enough that if you decide to run it in production, you can probably just apply most of the changes from the v11 branch yourself.

But I agree it's not a very good look to code-drop something on a .2 release when there's been 2,5 years of fixes.

The diffs are non-trivial (EDIT: only included changes in directories where conflicts are most likely to occur):

    $ git log --oneline REL_11_2..REL_11_12 -- src/backend src/include ':!src/backend/po' | wc -l
    536
    $ git diff --stat REL_11_2..REL_11_12 -- src/backend src/include ':!src/backend/po' | tail -1
     352 files changed, 14651 insertions(+), 7078 deletions(-)

Even if the conflicts are minor, it's going to be annoying to try to work it out. If you are hitting a specific crash, there's a good chance you can backport the fix cleanly, but I doubt you can just pull in all of the fixes proactively without some knowledge of the details of the fork.

I haven't really looked at the details... perhaps PolarDB already has many (or all) of the fixes since 11.2. Also I haven't actually tried a merge, I'm just assuming the difficulty based on the number of diffs (and my experience doing minor version merges in the past).

(Disclaimer: I work for Citus Data. Citus takes the approach of a pure extension, which means it works on unmodified Postgres, and minor upgrades typically don't interfere at all.)