I'm a simple guy. If a website I visit uses any kind of captcha other than Cloudflare's Turnstile, then I close that website and don't use it ever again. I'm not interested in wasting five minutes picking which squares have busses in them because ReCaptcha has decided I have to do the captcha 200 times.
Is that cloudflare one the one that just verifies you're human automatically? Like it pops up with a check box you sometimes don't even have to manually click? How does that one even work? 🤔
The code basically tracks mouse movements, or the lack thereof. If a bot is using a cursor, it might move in a straight line at constant speed to the "I'm not a robot" checkbox. Most bots though just check the HTML and jump directly to the checkbox. There are other checks it might do as well, e.g. the user-agent of the browser, whether the user came from a search engine, etc.
That being said it's that not difficult to break, e.g. Puppeteer has a plugin specifically for getting around Captchas and Cloudflare's offerings.
All this is to say: automatic captchas are better at allowing legitimate users than they are at blocking bots entirely.
It checks user agent to see if you are using something generic in a user agent switcher. It gives me fits sometimes if I leave it on chrome from Firefox too long.