demote bug maybe?

my main role is jungle and i was at 0lp, played a game of top lane, lost, and my demotion left me at 76 lp even though you only lose 3 or so for lp splash. I'm not 100% if this is a bug or not but it just seems kind of dumb that you lose 20+ lp from a -3lp splash when you're at 0.