Faint yellow spots on screen (see image)

Please see the top right corner earmarked in blue scribbled boundaries to highlight the yellow spots.

Is it because of,

a) Manufacturing defect due to poor gluing of the LCD panel, OR

b) Wear and tear of the LCD panel due to usage over time. I bought this iPhone XR in July 2018, so 3 yrs running. Seems like a short run window for this sort of LCD panel aging issue cropping up. (If it’s the underlying case)

c) Software issue

Few disclaimers:

1) Haven’t had the screen replaced, nor the phone underwent any repairs.

2) Just to show the yellow spots, I increased the brightness to 100% (yellow spots are prominently visible at this rate of brightness). Typically, I keep my phone brightness to <=40%.

3) Have rarely dropped the phone. I protect the body with Pitaka case.