Introduction: There's a good feature in v2rayNG which I guess the dev is not aware of. Maybe it was not supposed to exist, though it exists by itself haha :D After each sort, invalid configs get sorted by their last availability time. It happens because when a config becomes unavailable, it gets sorted by its previous index in the list, from previous sort. Therefore the previous index plays the role of last availability time, for unavailable configs.

Why is it good? Because unavailable configs which are actually alive, will sometimes become available again and move up, so, after getting unavailable again, they will move to the top of other unavailable configs, as the first config at the top of them. (It happens a lot for all configs in Iran, every 30 seconds) And those invalid configs which are really dead (unavailable forever), will get moved downer and downer after each sort, and they will stay at the end of the list as dead forever.

*** Now my feature suggestion: Instead of deleting all unavailable configs (the bad button which mistakenly kills healthy and alive configs as I have explained here), create a safer solution: A button (in addition to the bad button, or replacing it) which should delete a few last configs from the bottom of the list (the configs which are certainly dead and will never be available again are always placed at the bottom end of the list as explained in the introduction. So the solution to this problem has been created earlier!) Shortening the list with such a solution is safer than shortening the list by "DELETE ALL INVALID CONFIG" button which kills many healthy configs (after being temporarily unavailable in one test) too.

This implementation was impossible earlier, because new configs were getting added to the bottom of the list. But now it can be implemented because that problem no more exists. The implementation is very easy, and it is necessary in countries like Iran, in where configs get mistakenly unavailable/available frequently. By the word "unavailable", in this issue, I meant invalid config. By the word "dead", I meant, invalid configs which won't be available later again.

Related Issue: #2250