I'd say its just a matter of time before the algorithm finds and catches them.
About 10 years ago, I ran a forum with Adsense on it. It was family friendly content, but somewhere sometime someone managed to sneak in the word "dildo" in a joke.
Big deal right?
Well, I think it was about a year later when I got an alert in my Adsense account and an email from whoever was assigned to my account explaining the exact problem and letting me know how long I had to fix it before they banned my account. I fixed it immediately of course.
It can take a while to get caught, is my point.
Also, we know that some companies have backdoor deals with Google, and some get preferential treatment. If you perform well enough with Adsense with a legit online property for long enough, it's my understanding that you can get your own contact where they will help you split test things, make improvements, and even bend the rules for you, having your domain whitelisted and allowed to have more than 3 ads + the link ads. I've seen some of those in the wild. I think EzineArticles had that deal in the past.
If you use a 3rd party like ezoic or sortable to serve your ads you can usually have up to 5 adblocks. With sortable you can have floating adsense blocks as well. So some of what you're seeing is allowed.
Also some of them might not be Adsense blocks. I used to think every ad unit with the little blue triangle was Google until I looked into it more. (Not saying that's the case with you, but I wanted to mention it just in case.)