@Mattches So, if I understand you correctly, Bookmark All Tabs is designed to put all selected tabs into a separate folder, and there is no way to just direct them to an existing folder – i.e., a subfolder will be created under whatever folder is selected in the dropdown menu, and the bookmarks will end up there instead.
In which case a user who just wanted those bookmark in an existing folder would then have to move them to that folder in Bookmark Manager and delete the unwanted subfolder.
The concept (presumably it comes from Chromium) seems very odd to me.
E.g., I frequently store individual tabs as bookmarks in a specific folder (a kind of holding cell) that I maintain for that purpose, and disperse them to other bookmarks folders later. Apparently, if I decide to do this with a group of tabs I will end up with a subfolder in that holding cell folder that I don’t want or need.