The following signatures couldn't be verified because the public key is not available

~# apt-get update
Hit:1 http://security.debian.org/debian-security bullseye-security InRelease
Hit:2 http://deb.debian.org/debian bullseye InRelease
Hit:3 http://deb.debian.org/debian bullseye-updates InRelease
Hit:4 http://ftp.debian.org/debian bullseye-backports InRelease
Get:5 http://repo.mysql.com/apt/debian bullseye InRelease [12.9 kB]
Err:5 http://repo.mysql.com/apt/debian bullseye InRelease