24" iMac M1 Chip (2021) Display with Multiple Lines / Bands

As rkaufmann87 has mentioned you're experiencing what many are with M1 Silicon iMacs. The following topics illustrate the Silicon M1 iMac Display problem:

Screen Failure on 24-inch-iMac, M1, 2021 - Apple Community

Persistent horizontal lines appear on iMac Screen - Apple Community

Horizontal Lines on Screen of iMac, 24", 2021

Horizontal black lines covering bottom 3rd of 2021 M1 iMac screen

Grey horizontal patches on my M1 iMac 2021 model

Horizontal lines at the bottom of iMac(M1,2021) screen

Horizontal Lines on 2001 M1 iMac Display

Persistent horizontal lines and other issues on iMac M1 display

Many have taken their iMacs into Apple for a free diagnostic check and were told that it would take a replacement of the screen at around $600 US.

So far Apple hasn't announced a recall/fix for the iMacs. I recommend you take your iMac into the nearest Apple Genius Bar to have it diagnosed. This way you'll be in their database as having a problem M1 iMac and the might help push Apple into announcing a recall/fix for those iMacs.

In the meantime if the problem prevents you from using your iMac you can get an inexpensive monitor and run it off the iMac.

Yes, this has been reported many times on some of the 2021 24" iMacs. Apple does not have a repair program, it's a hardware failure. If you are in the USA, the repair costs quoted are in the $600-$700 range.

If you search these forums. you will find a few threads on the issue. I would urge you to contact Apple at www.apple.com/feedback to report the issue and request a repair program. They won't reply but if enough report the issue they may institute a program.