As mentioned in another post:
When researching the apt error connected librewolf I stumbled across this command:
For me this was the first time I encountered the command "extrepo"
It is a command to add 3rd party repositories that are curated by debian
You can use "extrepo" to add over 190 different repositories
This includes also the most used ones like for instance
Brave
Librewolf
WineHQ
vscode
google_cloud
speedtest-cli
proxmox
openvpn
and many many more.
See if you can use this "extrepo" command before considering manually adding a repository because it is a more secure way to add repositories.
This because adding repository keys is the most vulnerable step securitywise.
"extrepo" makes adding the repository keys less of a trust issue because they are added to your system by the extrepo command which implies that the keys and the repositories were checked first by debian.