It has to do with design of the vera Rubin telescope imager. Because it uses CCD instead of CMOS (which has become useful scientifically in the last few decades

It has to do with design of the vera Rubin telescope imager. Because it uses CCD instead of CMOS (which has become useful scientifically in the last few decades), it is susceptible to light bloom washing out a whole row of pixels or more. They could’ve adjusted for the possibility of satellite trails (which have been a thing since Sputnik) and taken into account the possibility that satellite constellations would increase over time (after all, there are several LEO constellations in orbit already for over a decade and mega constellations have been proposed since the 1980s and 1990s), but they chose not to. Which is fine, perhaps. Other mitigations are possible.