Thunderbolt 1-3 was an Intel standard. They gifted it to the USB IF where USB4 was made from it. Ongoing it's a certification program for USB4 / USB4 v2.0 nothing more.

In practice, every USB4 controller manufactured so far is certifiable and indeed with the 8840U generation AMD started certifying their SoC -- the only difference between the 7840U and the 8840U is slightly higher clock on the NPU and the TB4 certification. Compare https://psref.lenovo.com/syspool/Sys/PDF/ThinkPad/ThinkPad_T... to https://psref.lenovo.com/syspool/Sys/PDF/ThinkPad/ThinkPad_T...

or https://support.hp.com/us-en/document/ish_8110922-8110971-16 vs https://support.hp.com/lv-en/document/ish_10397818-10397862-...