Summary:
Drowned move by jumping on pressure plates. Drowned can find their way through the pressure plates, can move around, follow the villagers, but they do it by jumping.
I've checked a lot of other blocks and it seems to only apply to drowners and pressure plates.

Steps to reproduce:

1. Place pressure plates 3 by 3 blocks.
2. Summon in the center of the drowned.
3. Summon a nearby villager.

Observed results:
Drowned move by jumping on pressure plates.

Expected results:
Drowned will move around pressure plates normally like other mobs.

Video:
Minecraft Preview 2022-03-23 00-36-24.mp4