[dessant]

The issue is not compatibility with Chrome. Projects that were otherwise ready for the Manifest V3 migration and have worked towards that goal in the last few months can no longer proceed with the migration, their work has been made obsolete. The code we wrote no longer works, and we don't even know how or if the issue will be addressed before the next major Firefox ESR release. If a solution is not released in the next few months, this issue will prevent some projects from migrating until the end of 2024, or they will have to contend with dropping support for Firefox ESR.

I hope reading the linked pull request thread and the comments here will make it easier to see what went wrong, and why listening to the people that work with these extension APIs is important.