I have this working flawlessly with 5.10, just follow either the original tutorial [HowTo] get legacy 340xx NVIDIA drivers back or, if you need a later kernel, check @DAC324 's solution in the link I posted above.
Update: When using the modified PKGBUILD you have to edit this line:
+pkgrel=28
and provide the correct version of the nvidia-340xx-dkms pkg that you want to install, currently we are at 36 I believe.