The inverse square law is mathematically insignificant, why do you think you can still be blinded by a mirror? The source doesn’t become the mirror, the math is still calculated from the source, you need to account for the mirrors refraction in the calculation though.

That depends on the mirror, but I get the point you are making. However the light reflected off the mirror going to be subject to the angle of incident of the mirror. These are concave mirrors with specific focal lengths, not in the range of kilometers, but the range of meters. The efficiency of these mirrors is going to be far far far far far lower than 1% at a distance of 400,000 meters.

You’ll get far more energy to the ISS if you use a laser pointer than if you use a mirror, even if thousands of times as much energy is being reflected by the mirror.