Is this a bug or something?? LP Bugged??

So, i won a game, stomp enemy team and in the end i go check and i won 8 lp, thats rly strange because i never won 8lp and i was winning 19lp constantly, and my team and the enemy team were ranks near mine so what could this be, can anyone explain me? [Screenshot of the end of the game]( (Everyone in the game was in the same rank as me gold5, gold 4, silver 1)
Report as:
Offensive Spam Harassment Incorrect Board