ViaBackwards VS DropHeads

then you should use ViaBackwards in combination with ViaVersion.

You may want to try submitting a bug report here

Also, consider using one of the Paper forks that includes further performance improvements. For 1.18.2 two options are Pufferfish and Purpur. Pufferfish has a lot of optimizations, but now Purpur actually downstreams Pufferfish too so it includes all of its improvements (plus a ton of other features which are optional and turned off by default). Purpur as far as I can tell is currently the most complete Paper fork, the only downside in my opinion is that they only support the latest versions of Minecraft. Previous Purpur versions have not been patched for Log4Shell. Since you are running 1.18.2, this shouldn't be a problem, but keep this in mind for the future - if using Purpur you'll want to update soon after a new server version releases to continue getting support, or switch to another Paper fork (which shouldn't be a problem as long as you don't use any of the optional Purpur features). I personally prefer just using the latest version anyway though, and then I use ViaVersion plus ViaBackwards to support older clients.

Probably not your issue, but just because I heard of it, there's an issue with the inventory desyncing if using ViaBackwards.

I am setting up permissions on my server and I cannot for the life of me figure out how to set up permissions for the custom droprate boost on DropHeads. I want certain permission groups (using a luckperms track) to have a higher head drop rate. The configuration file for DropHeads is available here, specifically "custom-droprate-multiplier-permissions" on line 198. I have tried every single possible permission configuration possible and can not get it to work, the drop rate remains unchanged at the default rate. I can not find a working example online, and I am completely lost at this point. Does anyone have a working example?