Expected behavior:

Mobs that can float (Creepers, Villagers, etc) in water can walk out of it if there is an adjacent block at water level.

Actual behavior:

When the water is deeper than one block, they cannot pathfind out of it, even if there are blocks at water level. Placing a block such that there is a spot with just 1 block deep water will immediately make mobs pathfind to that and walk out of the water without issues.

Replication/Attachment:

Vindicators in this setup are not able to get to the Villager, since the pool of water is 2 blocks deep.