I have several concerns related to attachment file dialogs: (running Ubuntu 20.04 on Xorg installed via snap; using wayland etc. did not change any of the below)
symbolic links to directories are not working; they are treated as files; this is very annoying when trying to attach files (particularly with the above!): you double click the folder and it attaches a (useless file, unwanted) file instead
no icons are shown on my system in the file dialog (see attached screenshot; this forum post for the same effect: LINK); this slows down the navigation; strangely enough, a single filetype has an icon: key files ???
the file dialog does not differ between files and folders by default (suggestion: Folders first as Default Option - must be checked via right click every time a new file dialog opens! noticeable also in the attached screenshot, where calc is a folder and demo.ipynb is a file etc.)