Throwing a splash water bottle in the nether works and can put out fires in the nether, this shouldn't be allowed as water cannot be placed in the nether, a bucket of water cannot be used in the nether and so should a throwable water bottle.

How to reproduce

Start by crafting a splash water bottle

Then teleport to the nether and try using it, its gonna work and can also be used to put out fires in the nether.

Observation Throwable water bottle can be used in the nether
Expectations The nether is a very hot place and water should easily dry up in the nether.

Please watch these 2 videos explaining the difference between a bucket of water and a splash water bottle in the nether.