Following file described Package.gz size as 1126689.
https://developer.download.nvidia.com/compute/cuda/repos/ubuntu2004/x86_64/InRelease
Actual Package.gz size is 1127072.
Cause this difference, apt command fails.
Sorry for my poor English.
The repo metadata mismatch issue is now resolved.
Duplicate of https://forums.developer.nvidia.com/t/unable-to-add-apt-repo-mirror-sync-in-progress/263504
See also on GitHub https://github.com/NVIDIA/cuda-repo-management/issues/10