Any idea why am i getting such error? and, how could I fix it?

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys E298A3A825C0D65DFD57CBB651716619E084DAB9

Executing: /tmp/apt-key-gpghome.QThU5VY9Yd/gpg.1.sh --keyserver keyserver.ubuntu.com --recv-keys E298A3A825C0D65DFD57CBB651716619E084DAB9
gpg: key 51716619E084DAB9: "Michael Rutter <marutter@gmail.com>" not changed
gpg: Total number processed: 1
gpg:              unchanged: 1

sudo add-apt-repository 'deb https://cloud.r-project.org/bin/linux/ubuntu focal-cran40/'

Ign:1 http://ppa.launchpad.net/marutter/rrutter/ubuntu focal InRelease         
Hit:2 https://desktop-download.mendeley.com/download/apt stable InRelease      
Hit:3 https://cloud.r-project.org/bin/linux/ubuntu focal-cran40/ InRelease     
Err:4 http://ppa.launchpad.net/marutter/rrutter/ubuntu focal Release           
  404  Not Found [IP: 91.189.95.83 80]
Reading package lists... Done
E: The repository 'http://ppa.launchpad.net/marutter/rrutter/ubuntu focal Release' does not have a Release file.
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.