https://gerrit.wikimedia.org/r/180028
https://gerrit.wikimedia.org/r/189927
Which is STUPID, because it's a styling class, used for multiple purposes.
It looks to me that this was already partly addressed by the styling of rellink and dablink, until these classes were removed from most hatnotes.
But as I told jdlrobson before, semantic classes can easily be added and most hatnotes already have them. If you HAVE to remove, then be more specific than .hatnote and consult with the community.
https://en.wikipedia.org/wiki/Template_talk:Main#Appearance_.28or_lack_thereof.29_on_mobile_browsers