It is coated with material called MLI that reflects solar radiation quite effectively- it has been tested on earth too, so no space fakes.
Becuase there is no conduction and convection heating, solar radiation is the only way to heat things up- so the MLI helps with that
And the real, major reason it does not make it to 2500 degrees- you see, the very scarce nitrogen atoms, and oxygen atoms are very easy to heat up. Bringing their temperature up to 2500 degrees is not hard for the solar radiation- it is only 1 molecule!!
However, for the large satellites made of metal- solar radiation can not heat it up as much. Imagine this- boil 1/2 a cup of water.
Now boil 4 gallons of water- takes much longer, doesn’t it?
Now coat the pan with special multilayered heat shields that block most of the heat- the water might not even boil.