Ed25519Signature2020 is an earlier version of a cryptographic suite for the usage of the EdDSA algorithm and Curve25519. While it has been used in production systems, new implementations should use edssa-2022 instead. It has been kept in this specification to provide a stable reference.
The current spec says, in https://www.w3.org/TR/vc-di-eddsa/#the-ed25519signature2020-suite:
On the other hand, the section on deprecation in the vocabulary introduces deprecation saying, in https://w3c.github.io/vc-data-integrity/vocab/security/vocabulary.html#deprecated_term_definitions:
In my reading this means
Ed25519Signature2020
should be considered as deprecated. Otherwise some of these texts must change...