Display shuts off randomly but turns back on after unplugging cable

So I’ve got that imac and it works fine, upgraded the CPU and put a SSD in it but it always had a bit of a weird issue. First it started randomly dimming, it was still full brightness but it sometimes dimmed for a while, a bit more on the right, then went back up again. I don’t think it’s the temps as the computer still ran fine. Now, the display randomly shuts off, black screen but the computer is still running. I sometimes use it as a second monitor for my PC and if I unplug the cable the display turns back on again (I assume because the monitor turns off the backlight and turns it back on again? Moving the brightness settings with the keyboard doesn’t help tho)

I was curious what could be causing the issue? I’ve narrowed it down to either the LCD control board or the display itself? What’s weird is if it was the display, wouldn’t it just not work or only work in some parts of it? Thanks!