Specious engine ratings?

I play my game. Then I go over the game with the Lichess engine (admittedly a great free service). Mid-game I make a move that maintains near equality of about 0.4. The computer suggests another move that will have a 5.4 positive advantage I make the move on the board to see what is next. Now the engine says the move only yields a 3.2 positive advantage. What gives. Thanks. Sorry this was a little long.

The in-browser engine stops analyzing at 21 plies (11 moves) unless you click the + button.

Engines are not perfect oracles, they provide an approximated score for the position. From a more advanced position they might give a different score.

@ambrona said in #3:
> Engines are not perfect oracles, they provide an approximated score for the position. From a more advanced position they might give a different score.

Indeed. If they were perfect oracles, they evaluation would be simply win/draw/loss.