Wikipedia says it is a correlation check based upon a public key based signature. How is that not a form of encryption? Google says encryption is a process that scrambles data into a secret code that can only be decoded with a unique digital key, which is exactly what public keys are for.
Unfortunately DKIM only supports rsa-sha1 and rsa-sha256 signatures (https://datatracker.ietf.org/doc/html/rfc6376/#section-3.3). It'd be nice to see DKIM get revised to allow Ed25519 or similar signatures.