Would the simple fix (clearing the flag in `module_free`) be a candidate for a backport to 3.8? This seems to be a regression from the previous stable version that also limits the usability of subinterpreters -- `asyncio` is loaded by a wide variety of libraries and so in general it's not easy to know that a particular subinterpreter hasn't loaded `asyncio`.   However, I concede that subinterpreters with variable lifetimes isn't a common use case.