Loosing point when winning games

Any reason as to why I am loosing point when I'm winning games?
Does lichess knows the difference between plus and minus?
In last case i was 1390, i won a game which credit me 18 points, instead going up to 1408, i went down to 1388. This scenario been happens on several occasion. Your feedback is welcome.

I don't see what you're talking about. For blitz, your rating before the game was 1376. You won, and got 13 points, bringing you to 1389. Where are these numbers you're referring to? Winning a game will never lose you points.