The OCI specification lacks a strict definition of valid tags.

I believe that image tags should support the full semver specification. To be clear, I am not saying all tags must be valid semver, I am merely stating that a valid semver should also be a valid tag.

There are some technical limitations on the Docker/Moby side, as the + character is not allowed. Hopefully ratifying the addition (upstream? downstream? not exactly sure of the politics here) will spur this along. The issue has been open for 5 years with no progress.

https://semver.org
distribution/distribution#1201
distribution/distribution#1202 (comment)