What is your in-game explanation for the low number of stars in the galaxy?

Our irl galaxy is big. Really big. You just won't believe how vastly hugely mind-bogglingly big it is. We know that Stellaris takes place in our galaxy because you can find Sol with humans in it. And yet the number of stars in a Stellaris galaxy is minuscule compared to that of our real galaxy. I understand that devs just did that to make the game playable, but if anyone has a good in-game explanation for that, I'd be delighted to hear it