I'm getting frustrated with all the websites now claiming Firefox is an "ad blocker" and paywall, captcha-jailing, and worse just for deigning to open the page

I'm getting frustrated with all the websites now claiming Firefox is an "ad blocker" and paywall, captcha-jailing, and worse just for deigning to open the page in Firefox. (I have zero ad blockers installed. I do have built-in ETP on and use a bunch of containers, neither of which is actually "ad blocking", just cookie confusing.)