I gave up on the Green Knight long before any dark scenes, if I remember rightly. It was unwatchable for other reasons.
But I'll add another peeve: why is dialogue so hard to understand nowadays? It always seems to be drowned out by music or explosions. (To be fair, since I got a soundbar specially designed for clearer dialogue it's been less of a problem.)
And don't tell me that it's my middle-aged ears that are going deaf. The couple who live next door are half my age, and their ears - and the ears of their very young children - are ruined by their loud, thumping music.
The issue of sound mixing is ... complicated.
Here's an interesting article on Nolan.
And here's an article explaining the issue overall.
TLDR; there's a lot of different issues going on, but one of the primary ones is that sound isn't being respected during the shooting process. Because people are so used to "fixing" everything in post, they aren't doing the things that they need to do to ensure that sound quality issues are preserved when shooting.