bpo-46006: Move the interned strings and identifiers to _PyRuntimeState. by ericsnowcurrently · Pull Request #30131 · python/cpython
Currently the interned strings (and strings created for _Py_IDENTIFIER()) are per-interpreter. This is causing some bugs because other objects which may hold a reference to the string are still global. So until we are closer to moving the bulk of the global objects to per-interpreter, the simplest thing is to move the interned strings (and identifiers) to _PyRuntimeState.