Got the invalid traffic email today and I call bull

I got an email today stating that my earnings dropped because of invalid traffic and I call bull. They didn’t go into detail about it either so help me pinpoint what’s been so invalid about the traffic. My theory is that they’re going to use this excuse on a lot of publishers to pay out less money. When I logged in to see if I had any policy issues, nothing was there. Adsense is a terrible company. Most of my views comes from a place that I know it legit. A community I built myself from the ground up for years.