On chess.com you can chain premoves, on lichess you can't(afaik).

So in theory, to the extent premoves explain the rating difference, the difference should be greater on chess.com assuming they have the same parameters in their rating calculations. Therefore it should be possible to perform an analysis to shed light on this. But someone would have to go recompute the 3 different ratings under the same system first to be able to make a sensible analysis.