Maybe I just got super unlucky or something is wrong with key fragments

So I used to get a key fragment every maybe 5 games that I won so I had a one in five chance to find a key and then suddenly I had won about 20 or so games and havn't gotten one until just recently and I'm really confused because I havn't seen a change, or if the 1/5 chance was a bug, a bug fix in the patch notes so maybe suddenly in 6.6 there's a bug that dropped to drop rate of the fragments signifcatly.