The Debian repository for Teamviewer is blocked right now:
Err:8 https://linux.teamviewer.com/deb stable InRelease
403 Forbidden [IP: [Removed as Community Guidelines]]
E: Failed to fetch https://linux.teamviewer.com/deb/dists/stable/InRelease 403 Forbidden [IP: [Removed as Community Guidelines]]
E: The repository 'https://linux.teamviewer.com/deb stable InRelease' is no longer signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.