Firefox Library: Batch section of bookmarks and typing a new tag append the tag instead of replacing the old ones
Using Firefox 94.0
The objective is to change the tags of large numbers of bookmarks. This is to organize existing bookmarks under new categories that help in finding them more easily.
Until some time ago, I used the Library (Ctrl + Shift + O) to first select a batch of bookmarks (whether or not filtered after an existing tag or another criterion); and typed the new tag in the field Tags: at the bottom of the Library dialogue window. If I had to change the tag, I simply wrote the new one; the old one was replaced. If I had to add a tag, I could repeat the old tag and add the new one.
Now, instead, my new tag is appended to each and every bookmark in the batch. This makes it impossible to delete the old tags, unless you do it one at a time. Both doing and undoing become unwieldy when you have tens or hundreds of bookmarks. Also, it defeats the purpose of streamlining, because the number of tags grows.
So, there is a difference in behavior between editing the tag of a single bookmark and the tag of a batch of bookmark. Is this intended? If so, how to work around that? If not, I presume this is bug.