Not neceseraly broken, it's just that people bearly started learning her combos, so there's been more Lisolette action going on. I think most characters get used about equally, kind of... Maybe not, but some got more play than other on the early stages of the game, while the ones that didn't seem to be getting a bit more now.
Exceptions are like.. Konoha, character that still gets played a lot. I've seen lots of less Saki players now, not like the game is that old yet anyway lol.
So yeah, Lis is not broken, you are probably watching matches that involve the same player using Lis. Happens.