Discrepancies are going to be found in any material, whether it's synthetic or natural. The shoddiest and the finest calf skin will both be different depending on the tanning process and the actual animal.
Nike/JB do indeed use real leather, as well as synthetics. As far as 1s are concerned, I currently have 94 chi's, tan pinnacles, lance mountains, and 2015 UNC's. All completely different materials, some real leather, some not.
Here's Nike explicitly talking about reducing their current consumption of real leather:
https://www.nike.com/us/en_us/c/innovation/flyleather
Here's a Nike cleat that uses kangaroo leather:
https://www.nike.com/t/tiempo-legend-vii-elite-firm-ground-soccer-cleat-BDw2WJ
Here's the product description stating that it uses real/synthetic/textile, depending on the colorway and materials: