That's what I meant. It tries to access a global variable 'y' and fails because there is none.
See also:
https://x.com/marekgibney/status/1817495719520940236
and
See also:
https://x.com/marekgibney/status/1817495719520940236
and
Messing with locals has been a long-time danger zone. I don't know how it is supposed to interact with exec - another danger zone - and I don't know enough about the changes in 3.13 to know if it's resolved.