Strange behaviour with glass like shader

Im pretty new to Blender and wanted to create a glass coffe cup but I’m facing problems with creating a glass like shader.

I just thought it would be enough to turn up the transmission value and bringing the roughness value to zero in the principled shader but it looks very strange. I then played with the IOR and the max light bounce settings, nothing helped.

Here is the *.blend File:

the shader is okay. It’s the unrealistic enviroment and the table that makes this glass weird looking.
Even if you can’t see the background from this camera angle, it is still reflected by the glass and illuminates the scene.
Try adding an HDRI map to the background, change the material of the table and try to play with the lighting.

I tried playing with the environment and some HDRIs and I noticed that it behaves correctly. The problem is that I dom’t like this look and the reflection of the environment in the cup. My goal was to make a cup that looks lile the cup in this tutorial:

If I haven’t overlooked something in the tutorial there is no HDRI or other environmemt than a simple one colored plane. But his cup looks a lot cleaner. Not so photorealistic but cleaner and easier to look at. Could the thickness or the steepness of the cup-wall make that difference?

The normals are wrong for the cup. Plate is ok. The way the cup is setup, you’re basically looking from within glass into a cup made of air.
Use viewport overlay/face orientation. The cup should show up as blue.

I have also thought about the normals. I didn’t know that you can see what direction the normals are pointing so I just recalculated the normals (Shift+N in Edit Mode with everything selected) but that didn’t change anything. Thanks for showing me how I can manually check and correct the normals.

Edit: I found my mistake. When recalculating the normals I accidently had checked the box “Inside” which caused the normals to behave strange.