I have been a long observer of 4Chan, though I've long been banned for the silliest of reasons.
I have a hypothesis that increased 4Chan traffic, especially on /b and /pol indicates popularity of the alt-right movement and its many subsets, but also there is an ongoing war between troll-fueled triggered outrage and efforts to address topics with reason. Arguing on 4Chan is like arguing with Evangelical or Catholic apologists, but the fight goes on, regardless.
Also rare images pop up in /hr and /wp which is like caramel popcorn to me.
Pretty much, just annoy or offend a mod. They have carte blanche on what they take down and who they banhammer. Then the process to appeal involves extreme levels of contrition which I ceased being willing to perform.
It has approximately the same moderation philosophy as Reddit. I see Reddit's problem as a matter of bias and over-policing, where the mods of 4Chan seem to have a philosophy of I have power, I can be an unapologetic asshole
E.g this wired article on 4chan's moderation mentions how a user who attributed the Buffalo shooter's radicalization to the site got banned for "complaining about 4chan."