I have the same problem in my 2018 Model X. First noticed the yellowing around the main screen in Feb, got worse so made an appointment in May. They texted me they cannot replace the screen as they are working on a fix: "it has been determined that this general appearance issue is not covered by the warranty and can be fixed by our upcoming procedure of reviving the display." Called up the service center and spoke with the manager. He told me Tesla is working on a process/device to "revive" the display using UV light. He confirmed that it is not a software fix, and they do not have a firm date as to when it will be available. Also told me the issue comes back even if you replace the screen. I am fine with waiting if this fix will resolve the problem completely. If not, I expect the screen to be replaced with a good one under warranty. I understand they are trying to cut costs, but they should simply go back to whoever supplied them with these crappy screens and ask for replacements/refunds. My 2015 Model S screen works beautifully, no issues there. The Model X screen has deeper blacks, better contrast but bad quality.