Zombie horses constantly move in and out of water and burn to death

The bug

Zombie horses seem to have two conflicting goals: leaving water, and entering water when on fire. The sunlight sets the horse on fire, so it pathfinds to water. When it’s extinguished, it then chooses to leave the water, getting set back on fire again. This repeats until the mob dies.

How to reproduce

1. Spawn a zombie horse in daylight near a river

2. Watch its actions over the next few moments

Expected results

It should get set on fire, move to water, and stay there

Observed results

It gets set on fire, moves to water, then immediately moves back out and repeats

Notes

I’ve attached a video with the GOAL_SELECTOR and PATHFINDING renderers enabled. I used a baby horse, since adult horses of all kinds have trouble making it to water (they tend to stop at the edge – this is reported in MC-115396 in the “additional mobs” section). Other mobs like skeletons that burn in daylight seek out water and stay there.