Comment by InfamousRece

For me switching to Python 3.11 was really tough because of various legacy stuff removals (like coroutine decorators etc). While my code did not use these, the dependencies did. For some dependencies I had to switch to different libraries altogether - and that required rewriting my code to work with them.

There was also some time in the past when async became a keyword. It turned out many packages had variables named async and that caused quite a bit of pain too.