Huawei invented most of 5G technology and could tailor the 5G standards to their implementations. Which is also why they were first to market with carrier equipment [1] and had the first CPU with an on-chip 5G modem [2].
[1] https://www.wired.com/story/huawei-5g-polar-codes-data-break...
[2] https://en.wikichip.org/wiki/Kirin_990