These are the 2 biggest problems with the new Open and Save file dialog windows:
Open files: The 20.04 version of this dialog always showed a preview of image files on the right side when I clicked that file. This was very extremely nice and useful but is gone.
Save files: When I want to change the filename in the Save file dialog, I can't. It starts to search for what I type in, even if I click into the "Name" field first, sometimes I can type 1 letter there but then the search function kicks in again.
I hate to say that, but I want to get the old file dialogs back. :(