sudo apt update - "NO_PUBKEY CB8D50BB77BB3C48"

This is very context specific. What exactly did you do?

There is no issue with Whonix repository currently.

There is no general “NO_PUBKEY” error. I couldn’t fix all the “NO_PUBKEY” errors in the world.

If other repositories such as the I2P repository has this issue then this can only be fixed by the maintainer of the respective repository.

Such as, if it’s the I2P related issue which was recently brought up, see the respective forum thread: