I can’t speak on behalf of the core team, but I believe we’d be more interested in making async deinit be the “opt into isolation” for deinitislizers. The same way as initializers do. There’s no real downside to making the deinit also be async as well as making that the isolated one. One could also argue for “isolated deinit” but that’s a somewhat new spelling we don’t have anywhere else…
This should all also work for instance actors, not just global ones imho