Hi guys!
@ undersc0re
I think that it would have been enough just to "apt autoremove dkms" too after removing the module rtl81xxau in order to totally get rid off anything linked to the old drivers.
Glad to know that you got there!
Did you noticed too that the USB is working much more "fluently" with this drivers?
@ Soledge
If you installed the dkms package previously, try to remove dkms itself and restart your system.