Question Monitor Stains

[aelson]

There are stains inside my monitor.

(LG FLATRON W2043S, a ~10 years old monitor)

This happened last year when i was travelling for a few months: When I came back home, I've noticed a stain inside the screen. Now it happened again, I was away from home for ~2 months, but this time it has gotten even worse (see images below).
I think it could be dead pixels (due to the screen being off for a long time) or dust inside of the screen. If it is dust, can it be cleaned (at a technical assistance) ?

 

[Ralston18]

This monitor?

https://www.manualslib.com/manual/243280/Lg-W2043s.html

Very much doubt that it is "dust inside the screen".

My thought is that the monitor is simply showing its age and deteriorating/degrading into its' designed EOL (End of Life).

Could also be due to improper cleaning, storage in harsh conditions (e.g., heat, other stuff stacked on the screen, etc..)