There was a discussion a few weeks back Recent order way too thick as well as further back Viscosity - How thick is too thick?
The gum change was implemented so unsweetened matched the thickness of vanilla mid v2.0.
A survey was carried out following concerns and most liked the thickness of 2.0.
It was then mentioned about the gum mix being reviewed given people using flavouring which adds to the thickness, this is not currently in for 2.1 as far as I know.