iPhone 16 Pro Max brightness capped at 80% after iOS 18.5 update

"Iphone 16pro max Brightness reduced to max of 80% after ios18.5 update"

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Q1. "[...]Setting up as a new phone resolved the issue. So something in the data didnt go well with the update.[...]"

A1. Report this Update Bug Fix to Apple:

Do your Part: These are just user-to-user forms. Apple barely reads the forums as it is on their own time and will. Apple will know nothing of this bug and its fix, if you do not spread the word to them. So, report it to Apple. They wont get back to you directly, but the more they hear about this, the more likely they will look into, knowing what is going on. They will know knowing of this fix, if you don't report it to them.

1. Go Here: Feedback - iPhone - Apple
2. Select: "Bug Report" for the "Feedback Type"
3. Comment: on the issue, the solution, and how you can across it.
4. Proceed from there as necessary.

Q2. "[...]I have done 18.6 and no chance.[...]"

A2. IMPORTANT: Back Up Today. Having just reset this, and fixed the issue. back up your iPhone. That way you can have something to restore it from, should anything go working with the install.

It surely is not iOS 18.5 or 18.6 because...

I conducted a thorough search of this forum using the term 'Brightness after iOS Update' and uncovered numerous posts detailing similar issues across various iOS updates. This suggests that iOS updates may not consistently be the root cause. Below are a handful of examples extracted from the search results:

• iphone 14 pro max screen became extremely bright and white blank screen afterios 17.6.1 update...
• Lost Automatic Brightness Adjustment option after Sonoma 14.0 update
• Re: Unable to change display brightness after iOS update
• Brightness not working after update 15.6.1 I tried to resetting all settings turning off auto brightness still did not work…. sometimes when I restart the phone brightness
• Brightness automatically dimming after IOS 14.6 update
• Why is my iPhone brightness low after updating to iOS 18?

It's not always the iOS update's fault!  Many things can cause phone problems.  If you tell people you think it's an iOS update, it might make it harder to fix or find a solution for the real issue.

Remember, the right question often leads to the solution!

Was/Is your device Jailbroken? If that's the situation, please be informed that attributing the issues to iOS updates may not be accurate.

iOS updates aim to enhance user experience, boost security, and fix bugs rather than disrupt core features. The majority of the issues after updates might stem from underlying, unmentioned factors. Updates won't typically alter personal data but may refine settings or features. Backup before major updates for safety. Review Apple's update details and backup advice for a smooth process.

Kindly consider checking your settings and addressing any device issues before attributing the issue to external factors. This could be a pure coincidence that the iOS update affected the iPhone functions.

Before initiating a standard iOS update, it's advisable to create a backup. Have you completed this step? If yes, proceed with the restoration from the backup.

See what each update does: About iOS 18 Updates, About iOS 17 Updates, About iOS 16 Updates, About iOS 15 Updates, About iOS 14 Updates, About iOS 13 Updates, About iOS 12 Updates, and so on...