In new Ubuntu 24.04.1 LTS it seems that the *.list files are obsolete, and only *.sources files are used. To avoid this annoying message you can add not mandatory field:

Architectures: amd64

somewhere in the beggining of the file. I did it for google-chrome and microsoft-edge repos:

Types: deb
URIs: https://dl.google.com/linux/chrome/deb/
Suites: stable
Architectures: amd64
Components: main
Signed-By: -----BEGIN PGP PUBLIC KEY BLOCK-----
 ........etc.....