Those multiple reports of the brown/yellow top on these panels are really bad.
I am very lucky that my Pg248Q does not have that problem. The reason I went with a TN panels is because of the horrible quality issues that the Expensive IPS gsync models have.
So you could retry to get an other version of your monitor or the PG248Q . It is not the case in every monitor.
I can try set brightness to 30 and switch light off. Mabe then you notice it.