Not so sure whether this is a bug with the new lighting or the new expected behaviour but -
Surface/BillboardGuis with LightInfluence 0 and AlwaysOnTop disabled with the new Voxel lighting is no longer consistent with 2D guis, they now look washed out.
The right image was the previous behaviour with Surface/BillboardGuis on Legacy lighting as long as the LightInfluence property was set to 0, regardless of any other properties.
The right image is also the behaviour on Voxel WITH AlwaysOnTop enabled and LightInfluence 0, however the left desaturated image is present if AlwaysOnTop is disabled with LightInfluence 0.
repro.rbxm (5.6 KB)