When entering water(entire body, not just legs), I found that it looks as if the player has night vision even though they do not.
This is about it on what the bug is.

Steps to Reproduce:
Step 1: Start minecraft
Step 2: Load a world
Step 3: Go underwater

Observed Results:
Underwater vision is bright, as if the player has night vision

Expected Results:
Vision is normal and the player can't see too clearly because of the fog and light

No, I did not have any resource pack which does anything to brightness.
Before I updated to 1.17 it was normal