403 Forbidden and "no release file" errors when I try to add a PPA for Lutris

Question

yarob@yarob-2184:~$ sudo add-apt-repository ppa:lutris-team/lutris
 Stable releases for the Lutris client
 More info: https://launchpad.net/~lutris-team/+archive/ubuntu/lutris
Press [ENTER] to continue or Ctrl-c to cancel adding it.

Hit:1 http://deb.playonlinux.com cosmic InRelease
Get:2 https://mega.nz/linux/MEGAsync/xUbuntu_20.04 ./ InRelease [2,441 B]
Hit:3 http://ppa.launchpad.net/chrdevs/figma/ubuntu focal InRelease
Hit:4 http://apt.postgresql.org/pub/repos/apt focal-pgdg InRelease
Hit:5 http://archive.ubuntu.com/ubuntu focal InRelease
Hit:6 http://ppa.launchpad.net/daniruiz/flat-remix/ubuntu focal InRelease
Hit:7 http://ppa.launchpad.net/deadsnakes/ppa/ubuntu focal InRelease
Hit:8 http://ppa.launchpad.net/graphics-drivers/ppa/ubuntu focal InRelease
Err:9 http://ppa.launchpad.net/jonathonf/python-3.6/ubuntu focal InRelease
  403  Forbidden [IP: 91.189.95.83 80]
Hit:10 http://ppa.launchpad.net/js-reynaud/ppa-kicad/ubuntu focal InRelease
Hit:11 http://ppa.launchpad.net/lutris-team/lutris/ubuntu focal InRelease
Hit:12 http://ppa.launchpad.net/numix/ppa/ubuntu focal InRelease
Hit:13 http://ppa.launchpad.net/papirus/papirus/ubuntu focal InRelease
Reading package lists... Done
N: Skipping acquire of configured file 'main/binary-i386/Packages' as repository 'http://apt.postgresql.org/pub/repos/apt focal-pgdg InRelease' doesn't support architecture 'i386'
E: Failed to fetch http://ppa.launchpad.net/jonathonf/python-3.6/ubuntu/dists/focal/InRelease  403  Forbidden [IP: 91.189.95.83 80]
E: The repository 'http://ppa.launchpad.net/jonathonf/python-3.6/ubuntu focal InRelease' is not 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.

Answer 1

The Python PPA from JonathonF is discontinued, so you have to remove it from the system and update packages lists by:

sudo apt-add-repository -r ppa:jonathonf/python-3.6
sudo apt-get update

About postgresql repository you have to check the CPU architecture of the installed system and maybe change related source.list line by changing its first characters from deb to deb [arch=amd64] and then update package lists again.