I just completed upgrading a monolith from Python 3.8 to 3.11 - no doubt many others in the same position with 3.8 going EOL. It was a monumental effort. I will say the huge majority of work was upgrading libraries that hadn’t been updated in years. I won’t go into the specifics of why we had chosen not to update these libraries earlier (unless there is interest), but I will say Python being as backward compatible as possible has huge real world value. More for the community and ecosystem than the language itself. For the people who care about PEP 760, they have their choice of linting tool to enforce this requirement.