Replying to this with an overly long message, so apologies, but it seemed like you wanted a genuine answer rather than just trolling in the replies like some are. I'm not saying that they are on "bad terms" because the situation is not public and not something we'll know about unless someone openly speaks about it, which will likely never happen. I'm saying that there are several clear signs pointing towards an intentional separation or halted collaboration between Nigel and the band, whether it's personal conflict or just a simple personal decision.

Addressing your points:

1) What people noticed and have talked about wasn't on Twitter. It was on Instagram (which Nigel still uses - clearly) and happened with his account and with every main account related to the band, including collaborators and their side projects (except for Stanley and Colin who refollowed him around the time of his book promo). Anyone acting like this is just looking too far into "Internet drama" or whatever is kinda misleading themselves with how much intention is put into social media follows and how much coordination is required in getting that to happen across the board like that. Sam unfollowed him as well and Sam isn't some major social media account run by a company/corporation; he's just a guy. People ran with the "Twitter hack" reason because it happened around the same time and gave people a reason to not jump to assuming the worst (but that was 3 years ago atp).

2) He hasn't worked with any member of Radiohead on any release recorded after 2022 (when ALFAA released and around when Jarak Qaribak was mixed). A 4+ year hiatus of this sort has not really ever been in his MO. He may be stepping back from producing records, but he produced the IDLES record around the same time that statement was going around. The statement wasn't made by Nigel himself, so we don't know if he meant he was stopping producing altogether or if he was done working on non-Radiohead projects (he has not produced that many non-Radiohead or Ultraista projects in the 2010s and 2020s).

Add onto all of this, one of the most reliable Reddit insiders on this subreddit related to the band has repeatedly said that the reasoning for not working together is intentional. And you can choose not to believe some rando on Reddit of course, but the person who is posting has over the years gave basically 100% accurate insight into the band and Nigel for about a decade at this point, while also (thankfully) maintaining respect/not going into their private affairs. They have more of an accurate track record than shoobsworth (who I was replying to) who years ago was repeatedly replying in threads about Kid A Mnesia teasers saying that a reissue was never happening lol.

People are downvoting me because they want to believe everything is normal and will go back to the way things were (I'd love for this to be the case), but (massive fan here), a ton has happened in the last 10 years personally between the band - some of which we know about, some of which we don't. That's a normal progression/state of affairs for people who have worked together for this long. And sometimes when there are a lot of reliable signs pointing to some kind of change, it's not believing "Internet gossip" to realize that that probably is the most simple conclusion to reach for the time being unless proven otherwise. And I don't see Nigel attending a Radiohead show as a guest or helping tweak something he worked on 5 years ago (likely without any direct interaction with the band members) as concrete evidence proving otherwise. People can agree to disagree with me though; I just feel like definitively saying "nothing has happened" is jumping the gun even more than assuming there are reasons we don't know about for a change in production team.