Not sure if it's a recent update, but seeing really bad grid like uniformity problems with my 65 inch q90t. It's really bad to the point it's distracting. When I play a xbox game and pan around, you can see the grid like pattern clearly. Is this a update problem? That is something I would have noticed before.
I can definitely understand your concern here. Let's try to alleviate some of the stress by trying this link: https://www.samsung.com/us/support/troubleshooting/TSG01202526/ If this does not help I recommend letting a service technician have a look. As we would like to gather additional information and look at this from a case by case basis please provide the full model code and the serial number of the device as well as your best contact phone number, name, and email.
