I'm surprised there isn't a thread about this
So around the 19 of the last december hiroshimoot decided to add new third party ads and a script that kills the site's CSS if you block them.
Rumors of malware and cryptomining ran amok but so far none has been confirmed or dismissed properly. And updating your adblock is always recommended.
Out of this a group of fa/g/s are developing a dedicated desktop 4chan browser https://github.com/siavash119/qtchan
I still have to try it.
Personally I abandoned 4chan and decided to get a life but 4chan's shadow still looms over me.