Sadly, its time to visit the Apple Store (not an authorized reseller) one more time! This time with your service paperwork in hand, talk with the service manger that you need your system fixed, and this is NOT a software issue its a problem with this given system and you want a replacement.
They will likely say No! But don’t give up! Speak with the store manager and then the regional managers (Service and retail).
If you don’t have an Apple Store near you you’ll need to call Apple and have your issue escalated. Don’t accept No! Keep pushing.
You also need to clean your system! A dirty system says you don’t treat it as a valuable item to you. And the person servicing your system we care less! Which you don’t want.
As to why your screen is failing. It’s likely overheating! I would install a good thermal monitoring app to watch things. I use TG Pro as it offers what you need.
Make sure you don’t block the vents on the side and back as not air flow will do you in! You will want to see if what you are running (doing) is pushing your system too hard. Apple (and Intel) did you a disservice with the design of this system as the CPU runs hot! And the location of the T-CON logic is too close to the heat so it gets cooked!