Are injury tables for hitting 0 HP are a common house rule? I can’t even remember the last time I read about a group using one, and I was subbed to multiple game tales groups on Reddit (including RPG Horror Stories).

If you’re trying to run a gritty game, I can understand wanting a player hitting 0 to have an impact. I don’t think injury tables work otherwise. And I don’t personally think 5e is a great system for gritty games overall. The rules for Lingering Injuries are in the DMG, though, so it’s not always even a house rule.