bpo-40512: Store pointer to interpreter state in a thread local variable by markshannon · Pull Request #29228 · python/cpython

That's good to know. Thanks for explaining. This might not be obvious to maintainers. Would you mind adding a short comment next to the declaration of _py_current_interpreter noting the constraint?

Also, this doesn't affect builtin modules, right? Aren't some of the modules updated here builtin modules?