Get this error when using apt update.
Failed to fetch https://nextdns.io/repo/deb/dists/stable/InRelease 403 Forbidden [IP: 188.8.131.52 443]
E: The repository 'https://nextdns.io/repo/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.