Do you have any add-on installed for managing the bookmarks? I am not aware of a function in the standard Firefox who does that.

No add-ons. After the 144.0.1 update, the example below showed up under each Bookmark folder: "Bookmarks in folder: 6"

Hi

That is not a thing that can be disabled in the Firefox for Android user interface.

I too find this of no use and it makes my display over crowded. My solution was to go back to version 143.

That has gotten rid of this annoyance. I also turned off "auto update" in Play store