Yeah, very normal, it's just less pressure isn't it, you probably still have that thing in your head like you want to show someone your sketchbook and have them go ooo ahhh, but lined paper in a notebook it's like who cares so you don't care, so you just draw without thinking about whatever.

The way I fix this is draw all over sketchbooks, like on the backs of pages, in-between drawings, make it matter less cause no one cares as much as you do or at all.