Ubuntu 18.04, dozens of 403 errors

We have a Ubuntu 18.04 Server, and someone reported issues with cloning from git (I checked, was not able to clone my own repositories), and I wanted to run an apt update, and even there ran into tons of issues:

sudo apt-get update
Get:1 file:/var/cuda-repo-ubuntu1804-11-0-local  InRelease
Ign:1 file:/var/cuda-repo-ubuntu1804-11-0-local  InRelease
Get:2 file:/var/cuda-repo-ubuntu1804-11-0-local  Release [564 B]
Get:2 file:/var/cuda-repo-ubuntu1804-11-0-local  Release [564 B]
Err:4 https://nvidia.github.io/nvidia-docker/ubuntu18.04/amd64  InRelease
  403  Forbidden [IP: 185.199.108.153 443]
Hit:5 http://dl.google.com/linux/chrome/deb stable InRelease
Hit:6 https://developer.download.nvidia.com/compute/cuda/repos/ubuntu1804/x86_64  InRelease
Err:7 https://packages.gitlab.com/runner/gitlab-runner/ubuntu bionic InRelease
  403  Forbidden [IP: 104.18.20.224 443]
Hit:8 http://de.archive.ubuntu.com/ubuntu bionic InRelease
Err:9 http://dell.archive.canonical.com/updates bionic-dell-beaver-pearl InRelease
  403  Forbidden [IP: 185.125.189.10 80]
Hit:10 https://developer.download.nvidia.com/compute/cuda/repos/ubuntu2004/x86_64  InRelease
Hit:11 http://security.ubuntu.com/ubuntu bionic-security InRelease
Err:12 http://oem.archive.canonical.com/updates bionic-oem InRelease
  403  Forbidden [IP: 185.125.189.10 80]
Hit:13 https://download.docker.com/linux/ubuntu bionic InRelease
Hit:14 http://de.archive.ubuntu.com/ubuntu bionic-updates InRelease
Err:15 http://dell.archive.canonical.com/updates bionic-dell-service InRelease
  403  Forbidden [IP: 185.125.189.10 80]
Hit:16 https://repo.anaconda.com/pkgs/misc/debrepo/conda stable InRelease
Hit:17 http://de.archive.ubuntu.com/ubuntu bionic-backports InRelease
Hit:3 https://repo.saltproject.io/py3/ubuntu/18.04/amd64/latest bionic InRelease
Err:18 http://archive.canonical.com/ubuntu bionic InRelease
  403  Forbidden [IP: 91.189.91.15 80]
Err:19 http://dell.archive.canonical.com/updates bionic-dell InRelease
  403  Forbidden [IP: 185.125.189.10 80]
Err:20 https://packages.cloud.google.com/apt kubernetes-xenial InRelease
  403  Forbidden [IP: 142.250.185.78 443]
Ign:22 http://developer.download.nvidia.com/compute/machine-learning/repos/ubuntu1804/x86_64 InRelease
Hit:23 http://developer.download.nvidia.com/compute/machine-learning/repos/ubuntu1804/x86_64 InRelease
Hit:24 http://repo.zabbix.com/zabbix/5.2/ubuntu bionic InRelease
Reading package lists... Done

For every Err:, I have something like

E: The repository 'https://packages.gitlab.com/runner/gitlab-runner/ubuntu bionic InRelease' is not signed.
E: Failed to fetch https://packages.gitlab.com/runner/gitlab-runner/ubuntu/dists/bionic/InRelease  403  Forbidden [IP: 104.18.20.224 443]
N: See apt-secure(8) manpage for repository creation and user configuration details.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.

I don't even know where to start debugging this. I have updated the ca certificates, and rebooted the system, but that did not change behaviour. When opening a link (e.g. https://packages.gitlab.com/runner/gitlab-runner/ubuntu/dists/bionic/InRelease), it looks like it works fine?

What steps can I take to resolve this?

This can be because the repository is down or unavailable or they have changed their url or simply a network issues.

Here what you can try:

• Go see if the repo are down or unavailable with a web browser ( which you already seem to have tried )
• See if the url or auth method has changed, you can see that in their documentation and if there is, update your apt accordingly
• Check your network to see if they are configured properly
• finaly if none work you can try using different repositories here https://help.ubuntu.com/community/Repositories/Ubuntu