[Help Needed] Skyrim brightness suddenly bugged

Hey everyone, I could use some help.

I have been playing (modded) Skyrim for many years and normally am able to handle whatever bug the game throws at me. A while ago the game started to get the brightness messed up. I have been using an enb for a while, but it probably isn't the cause. When I run the enbm the game is far too dark, but when I disable it, the game is far too bright. Originally this only happened when entering caves or other interior spaces. I discovered, that loading a previous savegame outside the interior and then loading the interior save fixed the issue 100% of times, so I just started using this as a workaround.

However the issue changed and now the bug started no longer occuring when entering interiors, but rather when loading a savegame for the first time after starting the game. The reload trick worked as a fix still, so I just learned to live with it.

However the issue has now become worse. I installed a "new" gpu into my PC, which I know runs fine, but suddenly the reload fix doesn't work for the bug anymore and my game is stuck in a perpetual state of either strangely dark (with enb) or bright (without enb). Screenshots in my comment below.

Does anyone know the bug and how to fix it?

Note that I have sorted my mod order through Loot and made sure, that everything is compatible. The only thing I could think of, is that I tweaked the uGrid settings some years ago (I know, it's a deal with the devil), but this shouldn't really affect lighting from my understanding of the game.