Double check the PR is eligible for backport as per this linked page.
Verify that the backport PR does not add a cluster version nor a version gate.
(i.e. it does not make changes to
pkg/clusterversion/cockroach_versions.gonor does it contain checks that compare the current version to one of the newer versions.)
Ask on #engineering if you need details about why backports must never add cluster versions or version gates.
Check the release notes in the commit messages, to ensure they are applicable to the branch (if a release note refers to another change / PR that is not being backported, or that may be backported later, suggest a rephrasing.)