I'm seeing this issue too, and I haven't been able to figure it out. I was able to reproduce the issue on the iOS 15.5 beta as well. I filed a feedback ticket about it (FB9971866)

It looks like this issue has been fixed in iOS 15.5 beta 2.

@vanvoorden yes, I am building from Xcode 13.3.1 to my device on iOS 15.5 beta 2 and the issue is not reproducible anymore. The issue started for me in iOS 15.4 (19E241). I don't think there is a workaround in code. I filed a TSI on this issue and I was told "There is no workaround DTS can provide".

@jsponger Thank you, I had completely overlooked the size/contrast settings for Full Keyboard Access.