Skin club a scam?

I ran a test on Skin Club to test their percentages. I used the F is for Family case. In this case, there are two main skins that have the highest percentage, one worth $0.04 (31%) and one worth 0.35(68%), which is worth the same amount as the case. I opened this case 13 times and got the 31% skin 8 times and the 68% skin 5 times. I then calculated the chance of this happening with Chat GPT, which gave me 0.00434%. So either I am extremely unlucky or their percentages are completely wrong. If so, is there a rule in their terms and conditions that allows them to do this?