@latexluv Most likely there is a problem with the modelling of your glass-liquid system. Extract the inner surface of the bottle up to the height of the liquid fill. Use this newly generated geometry as your liquid, close the hole on top as this will be your liquid's upper surface , reverse normal direction  - normals need to point outwards for liquid surfaces in contact with the bottle, in most cases the normals of the liquid's upper surface LUS needs to match camera's y position relative to the upper surface in a xyz-coordinate system, e.g. camera y < surface y --> normal direction LUS (-surface y) / camera y > surface y ---> normal direction of LUS (+surface y)   - and apply liquid material. Check this link for modelling glass-liquid systems and proper setup of polygon normals. hXXp://XXX.3dmayatutorials.com/l_glass.htm

Test render with some DOF in the making. Couple of hundred samples.