stoically, the maintainer and creator of this extension unfortunately passed in early 2023. There's a new fork available[0], linked from github[1].
I briefly discussed this extension and how to proceed after the passing of a maintainer with Mozilla staff in their Extensions and People teams at FOSDEM this year, but there was no real procedures in place at the time of our chat.
Yes, that's truly sad that he passed. It is fortunate that he left that open-source project, where others can pick up the torch. As the forks continue, it becomes a small tribute to him.