Bad Omen effect eventually goes away on its own

I am unsure if this is a bug or an intended feature, but if I get the Bad Omen effect by killing a pillager captain, if I wait long enough (between 2 and 3 hours), the effect just disappears at some point. I've gone AFK a few times, I've built some houses, I've gone mining... Eventually, the Bad Omen effect is just gone.