Your’re right.
There is this topic: KI has been downgraded graphically... again - #107 by GazRJ where someone, including me, pointed at some strange behavior came with S3.
One of the missing things is the wet effect disappeared.
Apparently many people never noticed that effect while other, including you and me, did.
During S2 the wet effect was animated and during heavy rain on Thunder stage the water was flowing on bodies (like it does on the stage floor even now in S3).
The “S3 wet effect” is only a switch making textures more shining.
In the linked topic there are also other things pointed/screened/filmed like missing clouds on jago stage, missing heat haze in cinder stage, missing green eerie atmosphere in spinal stage (which was present also in hisako stage except for the green color) and many strange behavior of colors and accessories in various stages.
As before, someone do not notice differences.