VyOS supported minisign signatures since 1.2.5, that was released in 2020. The plan was always to remove support for GnuPG once minisign signature process was well-established but we never got to that second part of the plan.

Since there are no supported releases without minisign signature verification support and keys in the image, this change will have no impact on add system image. Only people who use GnuPG for verifying downloaded images will need to switch to using minisign (if there are still any such people ­— minisign is a lot easier to use).