Can confirm that few days later the “wet” colors in bottom corners have completely disappeared. This approach completely fixed the “staingate” issue for us. Thanks.

Followed instructions provided and used cleaning vinegar. Took a while and repeated rubbing of some areas with fresh vinegar, but end result very good and screen as new. Only in two bottom corners either pressed too hard or got some fluid behind the glas that shows up on the display with different “wet” colors. Hope that over time - if it is fluid - this will evaporate/disappear. But still happy with results as it so much improved. Thanks for sharing this approach.