IS ANY ONE KNOW EXACTLY WHAT’S WRONG I’M DOING IN HERE!
FLIPPING THE NORMALS DUPLICATING THE LIQUID FROM INNER OF BOTTLE (for accurate size) subdivision 2x
You have a liquid and glass, so there are 2 light interfaces: air-glass and then glass-liquid. There should be 1 surface for air-glass and then 1 surface for glass-liquid and IOR values should be correct for those. Keep in mind that IOR values are usually given for air and whatever material. This is a common mistake to leave 2 surfaces where there should be one duplicating geometry that is supposed to be liquid.
So let’s say I have glass filled with some liquid that has IOR of 1.3. I would make a glass surface with IOR of around 1.45(various types of glass may have wide range of IOR values, it’s not just 1.5 that you get by searching online). That’s for air-glass interface. Now the other side of my glass would be the glass-liquid interface, so it needs to be correct. The way I remember is that if light goes from less dense material to more dense material, IOR is greater than one and if it’s other way around, IOR is less than 1. Normal direction is also important, so I would reverse the normals and would have light going from glass to liquid, the IOR would be 1.3/1.45 ≈ 0.897. I would need another material for the surface on top of the liquid where it touches air with IOR of 1.3 if the normal was pointing out. It’s not that important here because the liquid is almost not transparent at all, but the thing is… there is no gap between glass and liquid. It’s not visible in most cases(I mean I have no idea what weird geometries the bottom of the container might have, but generally):
You should cut the liquid out of the glass container basically:
But everyone duplicates liquid and they always have double surface? Yes! It’s extremely common mistake even amongst very experienced professionals!
YES! You were RIGHT i had double surfaces in glass bottle that was creating the issue also i had correct IOR value for both materials (But Thanks for the method of remembering the IOR values THAT SOUNDS EASY)
QUICK QUESTION: Do you had an issue with reflections on bottle of inside liquid?
because after making it single layer/surface of bottle, I HAD but then used the solidifier modifier on bottle which kinda solves the problem, WAS THAT A CLEVER MOVE OR THERE IS AN OTHER WAY AROUND??
THANK YOU SO MUCH FOR EXPLAINING IN DETAIL! 
The idea is to have the correct amount of surfaces so I have no idea how solidify modifier could not screw this up completely.
