I answer so few calls that come my way so I haven't noticed a white box but I'll keep an eye out now? what do you mean comes up? does it stay on the screen till the call is finished or just like a white pop up box that fades out?
A screenshot would be helpful, if you could replicate it. I never get a white box. However, there's a box when the phone rings if you don't set it to full screen. And some caller ID apps pop up a separate box with caller information.
All of a sudden, my phone screen won't auto-rotate and I can not find the setting in display or anywhere else in Settings. This is a Galaxy S8 with Android 9. Any suggestions?