Description of bug
The description of the new Distortion Effects option (found on a tooltip) reads: Strength of nausea and Nether portal screen distortion effects. At lower values, the nausea effect is replaced with a green overlay.
The green overlay is only shown in game when Distortion Effects is OFF, rather than "lower values".
Possible solutions
Make the green overlay show at values less than, say, 25%, to make it "lower levels".
ORChange the tooltip to something along the lines of Strength of nausea and Nether portal screen distortion effects.
At lower valuesWhen turned off, the nausea effect is replaced with a green overlay.
The green overlay does not only appear at 0%