That really depends on which philosophy you subscribe to.
The TL;DR is that existential and post-modern philosophy say it's varying degrees of relative, while everything anyone said before ~1800 was saying that facts were immutable.
One fact I can glean is that the data itself may be real (e.g., the wavelengths of light that hit your eyeballs) but the perception is a composite illusion of our mind (e.g., the fact that you just saw a kitty).
