From what I understand, they're removing all recommendations from the home page if you have watch history turned off, likely because they can't give you any decent recommendations without data to recommend from. All you'd see is the search bar.

Personally, I think this is a great change. Default YT home screen has some of the worst recommendations I've ever seen, and if I'm telling them not to track my watch history, I probably don't want to see whatever content they're promoting to the average user either.