I had a similar issue and I was able to narrow down the root cause of the issue. Setting Status bar is initially hidden to true in the Info.plist breaks the top safe area on iOS 26. I tested this on an iPhone SE (3rd generation), and the top safe area always returns 0 when the setting is true. If I set it to false, it returns 20. On iOS versions prior to 26, this issue does not occur, they return 20 for the top safe area regardless of the Status bar is initially hidden setting.

I was able to narrow down the root cause of the issue. Setting Status bar is initially hidden to true in the Info.plist breaks the top safe area on iOS 26. I tested this on an iPhone SE (3rd generation), and the top safe area always returns 0 when the setting is true. If I set it to false, it returns 20. On iOS versions prior to 26, this issue does not occur — they return 20 for the top safe area regardless of the Status bar is initially hidden setting. I was able to reproduce this behavior in this project. You can change the Status bar is initially hidden setting and run it on iOS 26 to see that the top safe area differs depending on this flag. This seems like an issue on iOS 26 beta.