If I create a new tramp connection (after calling M-x tramp-cleanup-all-connections), I see a strangely blank screen from after calling the command (say C-x C-f "/-:slc:") until the directory gets displayed. Please see the attached picture.

That blank screen behavior is new. In 26.1, the frame contents continue to be displayed while the command is running.

Does it happen also when calling "emacs -Q"?