Limit celling when i record vocals

hi i have something that seems weird to me
when i record vocals no meter how much gain ill add even if i hear distortion if i look at the master meter ill see that there is a celling at -3db
(when the channel on 0 volume and there is no plugins)
and if for example ill put the channel on +2.00db so the celling will be -1db
so i wonder what set this celling and why i need it?

here an example i record with full gain on purpose

Your ceiling is 0dbfs on the recording track…anything over that is clipped.
The stereo out shows 3db down because that’s how pan law works with mono to stereo.
You could raise the track 3db to get stereo out to 0db if you like (because no clipping internally in Cubase)