I was planning to just report one problem, but as I was recording, I had other issues too.
Problem 1:
This popup doesn't follow the system theme (dark).

Problem 2:
That popup doesn't close when you close the main popup. There is no way to make it go away unless you open the main popup again, and click the same button you used to open it to close it again.
Problem 3:
The buttons in the popup randomly stopped responding. I could not close the popup. or interact with any of the other buttons. And suddently it dissappeared again. I'm not sure what happened.
(Same video as above)
Problem/Suggestion 4:
It would be nice if it behaved a bit more like the built in Firefox translation feature, where if you clock outside of the popup, it closes. Or maybe add a setting to change this behaviour.
It is also quite a bit slower compared to the built in Firefox one. I wish it was a bit faster.
I expected the popups to follow the correct theme, be responsive, and close when they are supposed to.