Daniel himself said in a 2021 interview the weight of it suddenly hit him and wasn't fun, which impacted his acting the 2nd film. Essentially said too much knowledge about what people expect, thoughts on Bond as a whole, legacy, responsibility just hit him, whilst the first was honeymoon period.
It's pretty clear he didn't enjoy the experience as a whole. They get zero input on the dialogue, it's all completely planned out in such meticulous detail so far in advance that they basically get wheeled out for a few minutes of dialogue then it's waiting again.
Batista said Daniel wasn't happy in Spectre, no smiles, never seen, cast were never together, never talking or interacting with each other off camera because you're not needed as it's months or years apart for certain scenes. Whilst in Glass Onion he was the complete opposite and everyone was having fun, on and off camera.
It's not easy making these kinds of films, you get unimaginable wealth, recognition for life but you're totally limited as an actor for the best part of 15 years. You get zero creative input, everything is utterly controlled, it's a very limited character.
They need to reduce the complexity for little pay off and get these movies out every 3 years tops, it was 2 in Brosnan's era. Less by committee film making would also help.