iMac Screen Separating from Casing

Then you need to take it to your local Apple Store or local independent AASP to have it professionally repaired. I would recommend booking the appointment ASAP.

Also, like Allan yours is the first account I have ever seen of a 2012-2020 display separating from the case. Very odd!

Welcome!

Has the computer been serviced or even opened since new? Did you buy the computer new or used?

The screen is sealed to the case; improper resealing after service often causes the symptom you describe. This sounds like a computer that someone has serviced without installing a resealing kit.

Has the computer been exposed to high temperatures?

I've not see a post here since Apple moved to sealed-case iMacs in 2012 saying the screen is coming loose from the case. Most people can't get the screen to loosen without special tools. That does not mean it cannot happen, but history here says this is not a know problem.

Loking forward to your follow-up information.

The fix, is to contact Apple Support or your local Apple Store and have the display seal kit replaced.

Apple Support or Genius Bar Reservation and Apple Support Options - Apple

Your welcome and good luck.