Whoops. I should have read all the comments before answering Chris’s comment. Max explained far better.

Chris: What you are looking at is a smeared streak caused by the asteroid’s motion. This isn’t its shape. Note the stars are points. The telescope was tracking the stars, so that anything like an asteroid would be streaked because it was moving.

“ZTF, which is funded by the National Science Foundation (NSF) and other collaborators, scans the entire northern sky every three nights in search of supernovas, erupting stars, and other objects that otherwise change or move in the sky. As part of a NASA-funded program, ZTF team members search for near-Earth asteroids. When these space rocks speed across the sky, they leave streaks in the ZTF images. Each night, machine-learning programs automatically sort through about 100,000 images in search of these streaks, and then narrow down the best asteroid candidates to be followed up by humans. This results in about 1,000 images that team members and students sort through by eye every day.”