There are only a little over a million known asteroids. The link you provided is saying that the Vera Rubin Observatory is expected to find billions of galaxies

There are only a little over a million known asteroids. The link you provided is saying that the Vera Rubin Observatory is expected to find billions of galaxies, and says nothing about how many asteroids it is expected to find. https://catalina.lpl.arizona.edu/faq/how-many-asteroids-are-there https://catalina.lpl.arizona.edu/faq/how-many-asteroids-are-...