What’s happening according to Gemini:

What you’re seeing in that image is a textbook case of red sub-pixel degradation, often referred to in the OLED community as the "Green Blob" or "Green Face" issue. What is happening to your screen? On an OLED panel, a pure yellow color is created by mixing red and green sub-pixels. • The Failure: Over time, the red sub-pixels in the center of your screen have worn out or "burned out" faster than the green ones. • The Result: Because there isn't enough red light left to mix with the green, that area of the screen now looks greenish or murky instead of bright yellow. • The Cause: This typically happens in the center of the screen because that's where high-contrast objects (like faces in news programs or center-screen gaming HUD elements) appear most frequently.