iPhone 17 running on iOS 26.3 continually dimming the screen brightness.
Most noticeable after using from Nightstand mode but is now continually doing it after pushing the brightness back up.
If I take the brightness up to a little over 50% and then the next time I go back to open the phone it will be down to around 30%.
Auto brightness is off, adaptive power is off, tap to zoom is off.
Possible iOS 26.3 bug?
iPhone 17
There are some reports of bugs and some community members have found that TruTone, Night Shift, Reduce White Point and Attention Aware may be associated with the possible bug.
Another feature that will automatically dim your screen is auto lock. Just before it locks, the screen will dim. If it detects your Face (attention aware) it gradually increases brightness. I see my iPhone 17 PM doing this and I’ll see it dim out of the corner of my eye and I’ll glance at the screen and it brightens.
A suggested bug fix is toggling both white point and auto brightness on and off. True Tone also needs to be off. Some Focus Modes are also dimming screens.
If the phone gets warm (sunlight, gaming, 5G hotspot, charging, camera use), iOS will cap or reduce peak brightness to protect the OLED and internal components, regardless of your brightness slider.
In nightstand mode is it wirelessly changing? Once the device cools, brightness will automatically increase, but not all at once. The thermal management will only gradually increase brightness to reduce the rapid build of heat.
These systems are designed to protect the OLED screen, battery and other internal components from damage. It cannot be overridden by the user. CNET had an article about this just a couple of days ago.
Hi Bro!
Please check the following issues:
1- Check the screen protector (if any)
2- Close background applications (especially those with AI)
3- Test under similar lighting conditions.
Light sensor performance and other factors will depend on the ambient light and the application you are using. Please check.
Is Low Power Mode turned on? That would do it.
I would turnAuto Brightness back on, you have a setting intended fir people who are sight challenged.
Might have narrowed it down a bit more.
The issue seems to be related to Standby and I’m trying to decipher if it’s only one of the Standby screens that seems to iniate it.
Night mode is turned off and it’s set to turn the display off at 20 seconds.
charging via USB C cable connected to a 20w PD charger.
moose_miller wrote:
...
No one is Sight Challenged here.
So turn auto brightness back on.
No screen protector on.
No thermal issues, in fact it’s running lovely bar the brightness bug.
Nightstand via USB-C connection and not MagSafe or Qi2 etc.
Obviously I’ve powered it on and off.
I’m convinced it’s a bug in 26.3 as I’ve been through everything that’s been suggested on this thread before I posted, in fact it was the last thing I wanted to do was to ask.
moose_miller wrote:
Regarding the Auto Lock, when re opening the home screen do you find yourself readjusting the brightness setting back to where it was?
What affect did turning Auto Brightness back on have?
I’ve not really been able to duplicate your experience. I’ve tried repeatedly over several days and I’m not seeing what you are, I think.
Your most recent post makes me wonder if it’s related to your charging equipment somehow. My cable and charger are stock Apple. But I think you may be onto something and you should pursue it if you have the patience.
Both Low Power Mode and Adaptive Power Mode are OFF.
I would expect Adaptive Power Mode to definitely effect screen brightness but it’s been off since installation.
No one is Sight Challenged here.
Regarding the Auto Lock, when re opening the home screen do you find yourself readjusting the brightness setting back to where it was?
I’ve gotten in the habit of pressing the side button to lock my iPhone. I’ll try letting auto lock kick in and see what it does. I’ll post a reply in a few hours.
iPhone 17 iOS 26.3 continually dimming screen brightness?
