"JPEG" is short for Joint Photographic Experts Group, an ISO/ITU group that creates a lot of imaging standards. The JPEG image format you're thinking of is only one of the formats they've created.

The Joint Photographic Experts Group manages many standards, generally each called "JPEG [something]". The one we most commonly call "JPEG" is just one of them.

Reading that it looks like the point of JPEG-XS is to have near-lossless compression for raw photo and video data while having extremely high throughput.