It can be done by opening a PR, I haven't tried it yet, but I'm curious to try out https://github.com/uber/piranha or maybe hear some experiences if someone has used it
AFAIK, it'd only open a PR if the flag is fully enabled and has some heuristics to determine when it's safe to remove. Honestly, I haven't tested it but I'm curious to know if someone had either good or bad experiences.
If all the PRs are instantly rejected, that would be a bad sign, but I couldn't find someone who effectively used it. I mean, it's been around for a while but it didn't spread out, so that already gives me some hint
If the cleanup only happens if the flag is not used, then the "expiration date" is basically meaningless. You can either delete it or you can't. Who cares if it's expired or not.
I think expires is just a signal for a feature that should "potentially" be removed. I believe it's a good way to focus on the ones you should pay attention to. But, it might be cool if you could say "Yes, I know, please extend this for another period" (or do not notify me again for another month)