Starting kvm and switching to tty turns off display

There may be a slight chance it’s related to your solution to your other (xy?)problem.

Do read this man part and try to figure out if this is the case

s
The s option lets you set the screen saver parameters. This option accepts up to two numerical parameters, a ‘blank/noblank’ flag, an ‘expose/noexpose’ flag, an ‘on/off’ flag, an ‘activate/reset’ flag, or the ‘default’ flag. If no parameters or the ‘default’ flag is used, the system will be set to its default screen saver characteristics. The ‘on/off’ flags simply turn the screen saver functions on or off. The ‘activate’ flag forces activation of screen saver even if the screen saver had been turned off. The ‘reset’ flag forces deactivation of screen saver if it is active. The ‘blank’ flag sets the preference to blank the video (if the hardware can do so) rather than display a background pattern, while ‘noblank’ sets the preference to display a pattern rather than blank the video. The ‘expose’ flag sets the preference to allow window exposures (the server can freely discard window contents), while ‘noexpose’ sets the preference to disable screen saver unless the server can regenerate the screens without causing exposure events. The length and period parameters for the screen saver function determines how long the server must be inactive for screen saving to activate, and the period to change the background pattern to avoid burn in. The arguments are specified in seconds. If only one numerical parameter is given, it will be used for the length.

and this

 --powersave mode
           Valid values for mode are:
           vsync|on
               Puts the monitor into VESA vsync suspend mode.
           hsync
               Puts the monitor into VESA hsync suspend mode.
           powerdown
               Puts the monitor into VESA powerdown mode.
           off
               Turns monitor VESA powersaving features.