I'm getting the following error when trying to run apt update:

sudo apt update

Hit:1 http://ro-mirrors.evowise.com/ubuntu focal InRelease

Hit:2 http://dl.google.com/linux/chrome/deb stable InRelease                   

Hit:3 http://ro-mirrors.evowise.com/ubuntu focal-backports InRelease           

Hit:4 http://ro-mirrors.evowise.com/ubuntu focal-updates InRelease             

Hit:5 http://ppa.launchpad.net/bashtop-monitor/bashtop/ubuntu focal InRelease  

Hit:6 http://security.ubuntu.com/ubuntu focal-security InRelease               

Hit:7 http://archive.canonical.com/ubuntu focal InRelease                

Hit:8 http://ppa.launchpad.net/cappelikan/ppa/ubuntu focal InRelease     

Err:9 http://ppa.launchpad.net/wireguard/wireguard/ubuntu focal InRelease

  403  Forbidden [IP: 91.189.95.83 80]

Reading package lists... Done                      

E: Failed to fetch http://ppa.launchpad.net/wireguard/wireguard/ubuntu/dists/focal/InRelease  403  Forbidden [IP: 91.189.95.83 80]

E: The repository 'http://ppa.launchpad.net/wireguard/wireguard/ubuntu focal 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.

Any pointers? I haven't changed anything from last week when I ran the command (work machine so I didn't use it over the weekend).

General info: XPS13 | Ubuntu 20.04 | 5.7.1 kernel | Gnome 3.36.3