Hi folks, those who like just hassle hours and hours with nvidia-340xx-kernel builds, please note, that the version 340.108-3 does NOT build on kernel-version 5.10.0-6-amd64. No chance!
Also the official NVidia-*.run does NOT build! However, I downloaded manually all (still not official in the testing repo database) nvidia-packages from the repo with the version 340.108-10-*bpo* and Volila, they build like a charme and working without any problems. Maybe they should be released as fast as possible? Hope this helps. Best regards and thanks for the great work! Hans