testing: from 10 bookmarks which I tried it only changed 1 favicon in main bookmarks panel but on the TABs it is displayed properly with changed favicons. It is nice simple and easy to use favicon add-on.

Unfortunately I`ve never found 100% working favicon changer/manager yet so to be honest I would prefer to have it as built-in feature of the firefox even though I know it is not the main focus of this browser. Anyway keep up the good work, I hope after some tuning it will work better for everyone, cheers

edit: I`ve seen dev response in the comments that "The current webextension api doesn't allow changing favicons for bookmarks" but imho the best use of favicons is to create bookmark panel with icons only (favicon on the TAB is not so important for me for example).