https://wccftech.com/the-new-24-inch-imac-is-so-thin-at-11-5mm-that-apple-had-to-move-the-headphone-jack-to-the-side/

The new 24-inch iMac with M1 is so razor thin that Apple had to rethink where they were going to put the headphone jack.

Apple has kept the headphone jack on the new iMac but the computer itself is so thin at 11.5mm that the company had to move it somewhere else.