QOAL
commented
1 year ago I tried a hybrid v2/3 manifest with Firefox, and it was ok, but I strongly dislike the fact that you have to click to enable it on each domain. That also made it so the content script wasn't ready when the action popup was shown and sent a ping message to see if could function on the current page, so the user would have to close and reopen the popup. I think for now I will use manifest v2 for Firefox and v3 for Chrome.
Firefox now supports V3, however its implementation is slightly different as Firefox still uses background pages from V2, rather than the background services Chrome uses for V3.
Either more investigation is required or code for both implementations will be required going forward.