Fabric has a convention for higher mining levels, that being #fabric:needs_tool_level_x, where x is a tier number.

So in this case, the switch should say:
case NETHERITE -> new ResourceLocation("fabric:needs_tool_level_4")
(or a reference to said identifier in another class).

Fixing this would fix Alpha-s-Stuff/TinkersConstruct#81 in Hephaestus.

You might also want to include fallback for tiers 4 and higher in the isCorrectTierVanilla, since #fabric:needs_tool_level_x are honored for x tier.

https://github.com/FabricMC/fabric/blob/dc89771ba2df08038e77d8f80289203986785864/fabric-mining-level-api-v1/src/main/java/net/fabricmc/fabric/api/mininglevel/v1/MiningLevelManager.java
This class will save you a ton of trouble with the tiers.

probably fixed on 1.19, will be cherrypicked to 1.20, 1.18 needs a fix in ForgeTags

this is hopefully fixed on all versions now