My iPhone 15 plus all of a sudden has a grayish white centered circle on the right side of the screen.

"My iPhone 15 plus all of a sudden has a grayish white centered circle on the right side of the screen.: This circle sometimes appears to be blinking."

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Troubleshooting a Grey-Out Screen:

Reply with a Photo:

Provide a photo (not a sceenshot) of your screen. IMPORTANT: Block out personal information (i.e. names and time) by covering it with red-colored rectangles and such through use of the Photos app.

Getting this Serviced:

Take a screenshot of your screen. If this is not shown in a screenshot, then get this serviced. You have a one-year, out-of-the-box, limited-warranty with this. So, see if it can be fixed, and if it would be of no cost to you (if found to be faulty device).

A. To Set Up a Genius Bar Appointment:

Set up a Genius Bar Appointment (GBA) at your local Apple Store.

1. Siart here: Genius Bar Reservation and Apple Support Options - Apple
2. Scroll down to the Bottom of the page
3. Click the Get hardware help button
4. Proceed from there as necessary.

B. What to Bring:

Important: Bring some notes, your original proof of purchase, and create a backup prior to bringing it in. Though not required, bring the power adapter along, in case theirs does not work.  See More here: Get your iPhone, iPad, or iPod touch Ready for Service - Apple Support