@Sunspark @jordan
You're are both correct. Thanks.
Earlier today, I spent about an hour using the black Honor 400 Smart 4G that I bought as a Christmas gift for my nephew. Unfortunately I experienced head pressure and eye strain, which leads me to suspect the display uses PWM. This is baffling because my own gold Honor 400 Smart 4G, and another unit I tested a few months ago, have been comfortable to use with no eye strain symptoms. It’s as if the black unit has an entirely different screen.
I compared the software on both phones ( Android security patch, baseband, kernel version, etc) & they are identical. The only difference I found in the settings is in Battery (More battery settings) the gold unit’s manufacture date is August 2025, while the black one is September 2025. That’s the only discrepancy.
The difference in comfort is truly bizarre. I had a similar experience with the Realme 9 Pro a few years ago, my original 9 Pro was fine, but a second unit (green) had different display dynamics and calibration, though it still remained usable. The black Honor 400 Smart 4G, however, causes noticeable discomfort for me (a headband like sensation and sharp, strained eyes), sensations I usually associate with PWM.
I can no longer recommend the Honor 400 Smart 4G. It feels like a screen lottery and poses a risk for people sensitive to display flicker. I'm very sorry @Aquila or anyone else I may have mislead.
