I've been pestering my users a lot. When they uninstall, I beg beg begggg them for feedback. If they leave an email, I respond with thoughts/questions. I respond to reviews. I offer to hop on calls to give 1:1 support.
In summary, I've been doing my best to listen to users and make small changes.
Ultimately I've learned that the UX for the extension isn't great for first-time users, but once they get it, it's solid.