Hi, I know this does not cause any issues, but solving warnings is always good.

@Mixin target net/minecraft/class_4970$class_4971$class_3752 is public in ferritecore.blockstatecache.mixin.json:BlockStateCacheAccess and should be specified in value

Maybe you can solve this? I don't know much about Mixin but you probably need to add @Public or something together with @Mixin.

Fabric (actually probably mixin now that I think about it) is lying. That class is net.minecraft.block.AbstractBlock$AbstractBlockState$ShapeCache and is defined package-private.

Exactly. My guess is that something is making it public at runtime (maybe some access widener?), it certainly isn't public at build-time, which is what matters.

I agree that it's generally a good idea to fix as many warnings as possible, but in this case the warning seems to be a false positive. If there was some exclusion list of "I know you (Mixin) think this wrong, I actively disagree" I'd add it there, but as there isn't one (AFAICT) the warning will just have to stay.