When writing in the App the text is not readable in iphone 13 mini. ios 16.7
After pressing return the text is normal readable. See picture 
Bug: Text on Iphone 13 Mini not readable
Same problem after i updated to ios 17
This should be fixed in the latest beta update. Let me know if it’s fixed for you? And if not, in what situations are you seeing it?
It‘s fixed thanks !