I bought this monitor around 5 days ago.
I have been using it for 5-7hrs each day.
I never had the piercing headache like I would get when I used large (24"+) IPS monitors.
Right off the bat, the monitor image was much easier on the eyes.
I instead had different kind of issues - I call it the "VA kind of strain".
To give you'll an idea, these are the feelings I felt:
"wrecked, wretched, bad, disgust-ness, bittery, nausea, miserable, malaise, sickish, burnt out firey (head and stomach), irritated itchy eyes and stomach, buzzed head, disrupted/scrambled energy."
This was felt the strongest in the 2nd day after I bought it.
However, during the 3rd and 4th day these effects reduced significantly.
Like my body was getting quickly adapted to this.
And now it's the 6th day, and I was able to use it for 4hrs+4hrs with a break in-between.
I almost feel normal now using it, and I believe another few days it will be even better.
This is such a relief, because now finally I can use a monitor, and that too a 32" sized one (my favorite size).
Even now I get a bit woozy and scrambled after using it for many hours, but its not that bad, and I recover quickly too.
Another interesting thing is that, my eyes get a little red and slightly itchy sometimes, but in some other ways they are actually more relaxed and fresh using this monitor because I assume it is from the 3.5ft distance away from me, unlike my laptop which is usually only 1.5ft away from my face.
The settings I used were:
125% scaling/1440p/144Hz, Night light at 45% (I sometimes turn it off too), Brightness: 0-20.
I also sit around 3.5ft away.