This is an issue with your sun glasses presumably as the Flip 4 has max brightness of 1200 nits
Just like the Galaxy S22 Ultra, the Z Flip4 offers this option called Extra Brightness - it increases the maximum brightness in manual mode
So this seems a personal issue and not the Flip 4 issue as specs are similar to S22/Fold 4
The Galaxy Z Flip4 has two displays, something that is typical for any flip phone - be it a recent one, or from the golden age of the GSMs. There is a...
www.gsmarena.com
Display test | 100% brightness | | |
Black,cd/m2 | White,cd/m2 | Contrast ratio | |
Samsung Galaxy Z Flip4 | 0 | 505 | ∞ |
Samsung Galaxy Z Flip4 (Extra Brightness) | 0 | 802 | ∞ |
Samsung Galaxy Z Flip4 (Max Auto) | 0 | 919 | ∞ |
Samsung Galaxy Z Flip3 5G | 0 | 503 | ∞ |
Samsung Galaxy Z Flip3 5G (Max Auto) | 0 | 935 | ∞ |
Samsung Galaxy Z Flip | 0 | 377 | ∞ |
Samsung Galaxy Z Flip (Max Auto) | 0 | 596 | ∞ |
Samsung Galaxy Z Fold4 | 0 | 505 | ∞ |
Samsung Galaxy Z Fold4 (Extra Brightness) | 0 | 809 | ∞ |
Samsung Galaxy Z Fold4 (Max Auto) | 0 | 1000 | ∞ |
Samsung Galaxy S22 | 0 | 465 | ∞ |
Samsung Galaxy S22 (Extra brightness) | 0 | 757 | ∞ |
Samsung Galaxy S22 (Max Auto) | 0 | 982 | ∞ |
I just picked up my Wife's pink Flip 4 this afternoon from Samsung store and just tested it on the balcony here in sunny Malaysia , no issues