Lichess can draw on cheat detection software developed by the entire open source community, and is written for all kinds of games, not just chess.
I'm not sure that anything that identifies cheating in other games is at all useful for detecting cheating in chess. How many people in the open source community are developing cheat detection software for chess? Are they really doing that voluntarily, for free, more effectively than someone who is being paid to do that? Not all of the Chess.com Fair Play team is involved in improving cheat detection methods - some of them would be involved in applying the methods that have been developed, for example - but if someone is doing something clever in this space in their spare time, Chess.com would be seeing it and applying it as well.
If I had to choose one, I would choose chess.com due to the larger community and some functions that lichess doesn't have. Also chess.com ratings are a bit more realistic than lichess ratings. There are some proponents of having lichess though, such as studies. I have both to maximize my options.