I’m having the same problem. Was getting worse over the last year and in the last month, the problem has tripled. I need to scan through junk email box to make sure no legitimate emails accidentally been put in there, which does happen, so I can’t just ignore my junk email folder. With the amount of junk mail each day, it is becoming very time consuming.
Add to that, the junk email is now showing up in my inbox as well and that is new. While the amount of junk emails showing up in the junk folder has been increasing over the last year and surged in the last few months; having some appear in my inbox has only started in the last two weeks.
Something has changed. This is crazy. I have done all recommended steps. I have the mail protection on, I block, I never open the email, I forward to abuse@icloud.com, spam@icloud.com, report phishing to the recommended emails, I have rules set. Nothing helps.