minus LP?

So, after losing a game, I saw that it said i got 0 LP, and then (-10). I didn't understand what it means so I went into my profile and saw that i have -10 LP in flex ranked.

I then played a game and won, and as you can see from my screenshot I actually had -10 (which resulted in me getting only 16 lp and not 26) why is that? I think that's a bug but I'm not sure. I was b3 and skipped b2 right to b1 in my last promos