Although it may not have been indexed yet, but Modrinth App constantly wants to update the version of the mod for NeoForge 1.21.1, since the version name is identical to the version of Fabric 1.21.1:

This issue isn't there on Forge 1.20.1:

The version number is 3.0.0+1.21.neoforge, which is not the same as for the Fabric release.

The issue is gone.