version 3.9.21 "contains fatal issue on the startup. There is a workaround: grant an optional permission "Read and modify bookmarks" for this addon via the addons manager UI. The next release will become working without the permission."(c)developer

it's a shame to developer to push such version to production and does not provide fix as soon as he noticed it.

UPD: bug has been fixed in a few days, so the rating was fixed too.