Bees seem to get stuck when colliding with certain non-full blocks as if attempting to pathfind through them. In most cases, they will stay in that position colliding with whatever block they're stuck to until a player pushes them. I've encountered them being stuck on trapdoors, flower pots, and extinguished campfires.

I've also noticed this same behavior with Allays, though not nearly as often. Allays also seem to get themselves unstuck fairly quickly whereas bees don't.