Question 5500xt

I'm guessing your question is why is it not PCIe 4.0 x 8?

That would depend on your motherboard, only AMD 550 / 570 based boards and Intels latest motherboards support PCIe 4.0, if it's anything older then it will be PCIe 3.0. As rdg1101 mentions, the 5500 XT only supports an x8 interface rather than x16,