"Scan to Verify You're Human": Google's reCAPTCHA is trialing a new "experimental challenge type" which requires desktop users to use an Android or iOS device to be able to pass it
i encountered this for the first time today while attempting to read something on archive.today.
i confirmed that decoding the qrcode using a computer and following the URL it contains is insufficient; the error it gave directed me here which is what the linked screenshot is of.
the old type of captcha remains available too, for now: