Honestly, I couldn't wait to blog about this one. This is mostly for Ultrawide Monitors though. I am on an ultrawide - 49-inch monitor.
Anyway, if you've googled and found this, it means all of a sudden, your mac decided to use a different resolution for your ultrawide monitor. Half the time, one that doesn't match the resolution of your monitor. (things are blurred and scaled weirdly)
I can't say I know the reason why it does that but I do know there's a fix for that, which is simple. Your mac needs to forget this monitor (like they never met). I know you've unplugged and plugged in a couple of times but it still persists. This is because the preference for that monitor is cached somewhere and your mac uses it each time you plug it in.
Now, where will you find this cache file? You need to delete a file:
For me, it was -
If that doesn't work then consider deleting this other (This is will forget all previously connected display preferences to your computer) -
sudo rm /Library/Preferences/com.apple.windowserver.displays.plist
All you need to do is delete this file. Simple but you've probably been googling for hours. I did too. LOL