This was a bit unexpected.
https://petapixel.com/2018/05/18/the-original-canon-eos-m-can-shoot-2-5k-raw-video-with-magic-lantern/
https://petapixel.com/2018/05/18/the-original-canon-eos-m-can-shoot-2-5k-raw-video-with-magic-lantern/