This would involve authors verifying that they are who they say they are. This is important for all addons but especially those that claim to be from a company.
For example the DeepL addon (https://addons.mozilla.org/en-US/firefox/addon/deepl-free/) is made by AllStarE LLC (https://addons.mozilla.org/en-US/firefox/user/20069396/).
Do we know that AllStarE LLC is the owner of DeepL? Is this Addon officially made by DeepL?
Flathub (https://flathub.org/) have a similar system with their applications. This helps users identify applications that are officially submitted by or at least endorsed by the application developer(s).
This would help ensure trust and safety of users of Firefox/Thunderbird Addons/Extensions/Themes, etc.