I have a similar issue. I see cloudflare checkboxes all the time. Google makes me fill out captchas all the time. Sometimes it decides I can’t search, sometimes cloudflare doesnt let me past the checkbox.

I’ve checked my network. I’ve monitored egress traffic. There is no residential proxy. I’m not on a VPN. If anything, services should be able to track me entirely by my home IP that doesn’t change that often.

My best guess is that I’ve committed the crime of not allowing third party cookies? Or maybe the crime of not being logged into a Google account 24/7. It’s not browser or device specific. My iPhone is just as likely to fail the cloudflare checkbox as my desktop with Firefox + uBlock.