Recently got a new MacBook M4 Pro and everything works fine until one day suddenly noticing the screen started to be flickering and never stops, realizing it might be some problem happening, so started to try to see whether it's just a glitch or persisting issue.

Tried to do following:

• Turn off the external monitor off and then on
• Plug out the HDMI cable of the external monitor and plug in back
• Restart the MacBook M4 Pro

These all failed to work, the issue still happens. So was following different online links to see it works or not.

Fix 1

Following the question asked on BenQ website for M1, M2 chips before. Though it is for BenQ but may apply to other monitors as well (Dell in my case). 

I changed the Colour profile to Colour LCD. Didn't touch on Refresh rate as it is already 60 Hertz. With that, it seems working initially. However after a few hours, while was doing some simple stuff, the monitor started to flicker again. This fix doesn't work here.

Fix 2

In a subreddit Will Apple ever fix external monitor flicker on M1/M2 ?, some people suggested to download BetterDisplay and disable the GPU Dithering option.

With this option change, it seems there is not much improvement as suggested by other people. This method doesn't work too well.

Will keep looking for a better solution and refresh back here.