guix-verify expects all.SHA256SUMS but guix-attest produces codesigned.SHA256SUMS. Since all.SHA256SUMS makes more sense (as the file contains all the sha256sums, not just the codesigned ones), guix-attest has been changed to output a file of that name.
As a quality of life improvement, guix-verify can take SIGNER and use the signer's manifest as the base to compare against. This makes it easier to compare a single person's attestations with everyone else's and can make it more obvious when one builder is clearly mismatching with everyone else.
Lastly release-process.md is updated with a note about a gotcha that can cause a mismatch in the codesigned attestation.