I'm a complete beginner so I really don't know what is happening.
$\begingroup$ Welcome to the Blender SE! If you could rephrase your question by describing what you want to do and then describe what is actually happening it will help people trying to answer your question. $\endgroup$– 10 RepliesJan 12, 2019 at 2:59
$\begingroup$ Thank you, I have found the answers. Just first time seeing how blender interpolates difficult polygons. $\endgroup$– klaudchaserJan 13, 2019 at 1:27
Basically, quads are low-key made of triangles.
Quads have no magical ability to stay "flat" so if you move a vertex out of its original plane, it can't be a "real" quad anymore and so blender shows you the ugly truth: a quad is two triangles stuck together.
Generally you want to build models so the quads don't get bent much, but they often will a little, and that's ok as long as the result doesn't look bad.
$\begingroup$ Yes but how do I make it look the same on all 4 sides instead of this half and half? $\endgroup$ Jan 12, 2019 at 0:42
$\begingroup$ @klaudchaser, what you want is not clear, but it's clear that you can't get it the way you're trying, please show a drawing of the object you want to model $\endgroup$ Jan 12, 2019 at 11:29
$\begingroup$ @moonboots Oh I just never had the crash course on polygons/triangles, but no worries, I have managed to find answers on posts and around. Basically what happened was that it was a first time I see how blender interpolates difficult polygons, and all I had to do was knife. $\endgroup$ Jan 13, 2019 at 1:25