UPDATE: So resetting default preferences helped. But I checked the preferences file (not readable with editor). I then screenshot evry settings tab and compared with factory settings. There was no change then 1 addon: NodeWrangler. Deinstalling Nodewrangler didnt help, first the factory reset. So there must be a different option somehwere else which is also saved in the userpref.blend . Perhaps anyone else could imagine?
I followed BlenderGurus Beginner Tutorial, and in Part 4, Level 3: Realistic Liquid - Blender Beginner Tutorial I have following problem. In Viewport (Image right side) you can see the coffee shines more dark through the glass and has dark-reddish reflection on the plate/ground. In the Rendering the glass looks very greyish and there is a highlight reflection on the plate/ground as if there is some lightsource or coffee won't be rendered correct. The liquid is sized to fit between the both sides of the glass and I followed all material settings and couldn't find out where the problem is. Could you help me here?
Best Regards Sören
It should look like this in Render: (from tutorial)
Update: After the Answer of @Jachym: Still same false behaviour for me: