Drowned's pathfind AI will be buggy when Y＞63

The Bug

When Y position of the waters of drowned is higher than 63, the drowned's pathfind AI will change, just like another underwater mob.

Steps to Reproduce:

1. Set your gamemode to creative and fly to the sky.
2. Creat a big hollow cube and fill it with water.

   /fill ~15 ~15 ~15 ~-15 ~-15 ~-15 stone hollow

   /fill ~14 ~14 ~14 ~-14 ~-14 ~-14 water

3. Give youself a conduit_power(This step is not important but useful)

   /effect give @s minecraft:conduit_power 1000000 0 true

4. Set time to night.

   /time set night

5. Summon a drowned in the cube.
   -> The drowned will sink to the bottom.
6. Set your gamemode to survival and swim up.
   → When drowned find you, they will swim up and chase you.
7. Swim down to the bottom.
   -> When drowned close to you, it will stop attacking you and stand next to you.
8. Make a cut in the ceiling and swim out off the water and stare at the drowned on the water's edge.
   -> The drowned will ignore you and sink down.
9. Jump to the water, press and hold the spacebar to float on the water.
   -> When drowned close to you, it will stop attacking you and turn round repeatedly.