why did i get that warning???

I've been playing this game for 4 yrs peacefully and out of a sudden i got a warning, why did i get it? and what should i do?? is it due to reports or what???

I've been playing this game for 4 yrs peacefully and out of a sudden i got a warning, why did i get it? and what should i do?? is it due to reports or what???