Hey Sildur - a few questions/issues.
1) I noticed that this has been a bug in your vibrant shader packs for a while now - when logging off in the Nether, when logging back in, all entities and other random items like edges of objects and portal blocks are completely black. Interestingly this only happens when you fully quit the game. If I go to the main menu then come back, entities are fine and not pitch black.
I asked about this issue on the Optifine Discord and other people seem to have the issue. I also noticed that this doesn't happen with other shaders, including your Enhanced Default shader. If it helps, I noticed that clicking on another shader profile (like from lite to medium to extreme) doesn't fix the issue, even with identical settings.
2) I was able to figure out how to turn off raindrops, but I can't seem to find a setting to not have the distorted lens when underwater. I'm not referring to the fog but the actual lens distorting like waves of water are in my eyes. It's an interesting effect, but I've been playing a lot of Vivecraft lately and it makes anyone who goes underwater instantly nauseous. Is there a setting that I'm missing to be able to turn it off, or if not could I make that a feature request?
3) I know that the snapshot just came out yesterday, but I'm wondering if you'd consider adding blue fog to areas in the new nether that have blue fog in vanilla whenever that time comes. It's a really neat looking effect!