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:
Place pressure plates 3 by 3 blocks.
Summon in the center of the drowned.
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:
[media]
Fixed in 1.19.50 (but only for pressure plates. See MCPE-162275)