Lichess’s cheat detection is open source (like everything else on the site) [0]. The training dataset isn’t public, though, and it’s practically undocumented. If you look in the `modules/game` directory, though, you’ll get an idea of what sort of data that goes into the model. Besides the engine analyses, it also looks at the time spent on each move (the `Emt` type is short for elapsed move time).
[0] https://github.com/clarkerubber/irwin