Oh wow, I haven't seen that either (and I log into Twilio a lot 😄).
I think there has been an increase in friction over the years with Google's ReCAPTCHA, especially as it seemed we were being used to train bots rather than prove we were human. Plus, if you can train bots to recognise the items in the CAPTCHA, then bots can solve the CAPTCHA and they aren't much use any more.
Turning it into a game means you are looking for behaviour, not the ability to solve a puzzle. And it's more fun, which hopefully doesn't dampen the experience for the user quite so much.
I hope I do come across this test soon!
I saw it on another website. Forgot the address.
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