When you using screen recorder in Ubuntu, example
Peek – best for making short, silent screencasts.
Shutter – best for recording desktop sessions to GIFs.
Freeseer – best for capturing presentations.
Kazam – best for HD screen recording.
Gifine – best for trimming tools.
Byzanz – best for command-line management.
and output is Blank screen or black, only mouse cursor.
THis SOlution for Fix Screen Recorder Black or Blank Screen Recording Issue in Ubuntu
Open Terminal
– sudo nano /etc/gdm3/custom.conf
enter and input your password
in [Daemon] remove #
WaylandEnable=false
and in your keyboard, CTRL + X
and save modified with press Y