AoV uses reflection to make sure the player's capability provider is valid upon PlayerClone. After copying its own capabilities, it invalidates the provider (regardless of its previous state):

However, the provider is originally valid, so the code is not only unnecessary, but also breaks other mods like Vampirism: TeamLapen/Vampirism#577

I think in early Forge 1.14, the provider was originally invalid, which is probably the reason for your code, but that is fixed for some time now (MinecraftForge/MinecraftForge#5728). At least I did not have any issues with this since then.

If you still want to keep that code, please make sure to set valid to the original value instead of false.