The release tag client/v8.0.0 is for VolumeSnapshot and VolumeGroupSnapshot APIs and client library which are in a separate go package.

Urgent Upgrade Notes

(No, really, you MUST read this before you upgrade)

• The validating logic for VolumeSnapshots, VolumeSnapshotContents, VolumeGroupSnapshots, and
  VolumeGroupSnapshotContents has been replaced by CEL validation rules. The validating webhook
  is now only being used for VolumeSnapshotClasses and VolumeGroupSnapshotClasses to ensure
  that there's at most one class per CSI Driver. The validation webhook is deprecated and will be removed in the next release. (#1091, @leonardoce)

Changes by Kind

API Change

• Update API for group snapshots, easing the restore process. (#1068, @leonardoce)

Feature

• Adds validation rules into CRDs. Minimum required Kubernetes version is 1.25 for these validation rules. (#1073, @cici37)

Full Changelog

https://github.com/kubernetes-csi/external-snapshotter/blob/v8.0.0/CHANGELOG/CHANGELOG-8.0.md