Google stopped updates for Manifest V2 and announced that at the beginning of 2023 they will start enforcing Manifest V3.
This forced a lot of Chromium browsers extensions (myself included) to migrate to the new APIs which was a pretty big change, especially since there was no way back once released.
Luckily, Google Meet Attendance List is not heavily using Chromium APIs, the only challenge that I had to solve was switching from background.js to Service Worker and making sure that data persists on storage as the Service Workers have a limited life span.
On October 30th, version 4 of the browser extension was released.