Pls. help! Updating stopped functioning!

[UUUnicorn]

Please help! Updating stopped functioning. The result(s) is/are the following. Thank you very, very much in advance!
===========================
Install Updates Error log
===========================
Install Updates could not fetch the package cache information lists.
Go to https://www.freecinema2022.gq/forums/ and paste the log below into a new or existing thread for assistance.

============ Log ===========

Hit:1 http://us.archive.ubuntu.com/ubuntu focal InRelease
Hit:2 http://us.archive.ubuntu.com/ubuntu focal-updates InRelease
Hit:3 http://us.archive.ubuntu.com/ubuntu focal-backports InRelease
Hit:4 http://security.ubuntu.com/ubuntu focal-security InRelease
Hit:5 http://ppa.launchpad.net/libreoffice/ppa/ubuntu focal InRelease
Hit:6 http://download.opensuse.org/repositorie...untu_20.04  InRelease
Ign:7 http://repo.vivaldi.com/stable/deb stable InRelease
Hit:8 http://archive.canonical.com/ubuntu focal InRelease
Get:9 http://repo.vivaldi.com/stable/deb stable Release [3,831 B]
Hit:10 https://repo.skype.com/deb stable InRelease
Get:11 http://repo.vivaldi.com/stable/deb stable Release.gpg [833 B]
Hit:12 http://repo.linuxliteos.com/linuxlite emerald InRelease
Hit:13 http://ppa.launchpad.net/pinta-maintaine...ble/ubuntu focal InRelease
Hit:14 http://shop.softmaker.com/repo/apt wheezy InRelease
Ign:11 http://repo.vivaldi.com/stable/deb stable Release.gpg
Reading package lists...
W: GPG error: http://repo.vivaldi.com/stable/deb stable Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 9658E8044A3AA3D6
E: The repository 'http://repo.vivaldi.com/stable/deb stable Release' is not signed.