@Jandalf I recently had to reset my System Integrity Protection settings (csrutil clear) and once again ran into this issue, where my Razer device was not recognized. I have upgraded to macOS Big Sur 11.1, and I can confirm that the solutions by @avaddon and @rdabban, which had worked for me on 11.0, no longer work. Manually loading the kernel extension (the kextload command) will display the error code 27 "Extension with identifiers com.razer.common.razerhid not approved to load. Please approve using System Preferences.", but no pop-up or "Allow" option would appear anywhere on the System Preferences. Adding the Razer TeamID with the /usr/sbin/spctl kext-consent add R2H967U7J8 command showed me a pop-up, but with no "Allow" option, and no option to allow the kernel extension would appear in the System Preferences, so no good. I finally managed to make it work by temporarily disabling System Integrity Protection (SIP), as follows: Boot into Recovery Mode. This can be done by restarting your computer and holding Cmd+R on boot until a loading bar shows up. Once in Recovery Mode, sign in with your account and open a terminal. You can find it in the top menu under Utilities > Terminal. Disable SIP by running the following command: csrutil disable. Close the terminal and reboot (normal reboot, not into Recovery Mode). Open a terminal and load the extension with the following command: sudo kextload /Library/Extensions/RazerHid.kext. Reboot (normal reboot, not into Recovery Mode) and confirm that your Razer device is now correctly detected. Now we must reenable SIP to maintain system security. This should not break your device. Boot once more into Recovery Mode, open a terminal, run csrutil enable, close the terminal and reboot. You should now be able to load your Razer device AND have SIP enabled. Good luck y'all!

avaddon's solution works! Thanks a lot!