Finally finished Doom: Eternal: The Ancient Gods - Part 1 (damn, that's a long title).
It's too hard. It's been nerfed and it's still too hard. I played the main game on Ultra Violence and it was difficult enough to make me feel like any deaths were my fault, but if I did things right, then I had control. TAG1 was just too hard. That's why it took so long to get through. I dropped the difficulty to Hurt Me Plenty, and I was still struggling, and then I eventually went down to I'm Too Young To Die, which I thought was a little too easy (though I still died multiple times).
Having now moved on to TAG2, and again on UV difficulty, it feels right. I've still died a decent amount, but it's always felt fair - like I wouldn't have died if I hadn't made a mistake.
I didn't want to move on to TAG2 without finishing TAG1, but I think it was tuned badly. I know 'proper' Doom players only play on ultra nightmare with no extra lives and someone to punch them in the face and burn their computer if they die, but when a player who usually plays on hard mode isn't wiping the floor with everything on easy mode, then maybe they got the balance a bit wrong.