Methods like "Proof of Work" require the client device to solve a computational puzzle. While this does not prove a human is present, it makes high-volume spamming computationally expensive.
Some platforms are moving toward biometric verification (Face ID, fingerprint scans) or "liveness detection" (asking the user to turn their head or smile) to prove humanity. captcha+breaker
The use of CAPTCHA breakers raises several ethical and security concerns, including: Methods like "Proof of Work" require the client