So Arch made a new "lore" episode which is just bitching about the Emperor for 3/4 of an hour. And he talks about why there's no more HH videos.
TL;DW: He claims it was because he reached the conclusion that the new lore was worse for the 40K universe, so he lost the will to continue. There's also the claim that GW wants to remake that universe (ie, Emperor is the bad guy now) to go with social justice, which doesn't make sense (the Imperium were always morally gray) and is just the overused "everything is culture war". There's also the argument that he can't do anything big because GW will ban his videos, which would have had months ago if it was true.
Personally, I think it's just excuses and Arch wants to become a Sargon wannabe in his political channel and just dump the 40k channel alltogether. Problem is that his political channel is unwatchable and has 1/5 of his subscriber count, though at least it has a good ratio of subs vs. watches