This is a small bugfix to make CreativeCore more compatible with other mods that also provide the "net.fabricmc.api" packages; this simply renames the package to "net.fabricmc.moved.api" in order to make CC more friendly with other mods. In all honestly, all of these mods should refactor these classes to not include fabric directly, as most core mods simply use 1-2 classes as a structure for loading it seems (Glodium, Macaws & Creative Core are just some of the few that case this error).
The bugfix in mention is this one specifically: https://github.com/CreativeMD/CreativeCore/issues/187
I simply targeted Creative Core, as moving the packages in this library mod makes it friendly with everything else, this fix works for ItemPhysic Full, AmbientSounds 5 & Enhanced Visuals, Compatability with any other mods using Creative Core may vary, but these 3 are confirmed working. I will also not be fixing compatability issues if any arise, with other mods.