Hello @miko, that is correct, and that will really be a relief when Mozilla will enable favicon access in Firefox API, cf. https://bugzilla.mozilla.org/show_bug.cgi?id=1315616 and https://bugzilla.mozilla.org/show_bug.cgi?id=1411120, like Chrome is doing.

Please vote on those two bugs to raise their priority with the FF team !
When it's available, I will be able to drop the code for fetching the favicons :-)

Unsafe site messages are because you have bookmarked them, and so when BSP2 tries to retrieve the favicon from those sites, this creates the problem. When FF will make favicons available, that won't happen anymore. And meanwhile, the workaround is to disable favicon fetching as you have done, or to wait that BSP2 does all bookmarks, since this only happens one time, they are all cached by BSP2 after that.

Thank you, aaFn.