Areca macOS build-in driver is kext extensions, and Apple plans to deprecate kext extensions and uses system extensions instead. It is the reason of that warning message, for the unused system build-in driver. Apple does not allow us to touch kernel extensions, so you will see this warning until Apple remove the build-in driver. M1 Macs does not support kernel extensions. Areca Thunderbolt driver on the website is system extensions for M1 Mac.
Tags: ARC-8050T3U, mac M1