Check and tighten the display cable connections
Replace the video cable if it is damaged
Try a different monitor port on the computer
Restart the computer
Update the graphics driver
Roll back the graphics driver if the issue started after an update
Set the correct screen refresh rate
Lower the display resolution if needed
Disable hardware acceleration in apps that cause flickering
Close conflicting background programs
Check for Windows or system updates
Run a malware scan
Test the monitor on another computer
Test another monitor on the computer
Replace the monitor if the flickering continues
Repair or replace the graphics card if necessary