If you don’t use thunderbolt devices you probably will be fine.
Bios 2204 and above will update the tb firmware nvm to 36. It should be pointed out that 2305 and above are regression locked, and unless unlocked, will not downgrade to 2204 or 9901.
You only need to Use 9901 to downgrade the thunderbolt nvm from 36 back to 31. Why downgrade? As of nvm36, Tb2 devices are no longer compatible with maple ridge. Also, bios 2204 had a bug on some mobo models, where if xmp was enabled, the tb controller would malfunction if a tb device was physically connected, and the system woke from sleep. 2602 has resolved that nasty bug. Also, 2602 updated the cypress pd controller firmware, which addressed some weird connectivity issues (on the z690 formula at least) when the system was powered off and usb-c devices are physically connected to the system. On old firmware, the devices would connect/disconnect ad-infinitum. On the new firmware, this doesn’t happen any more.
But nvm36 + 2602 still has some bugs, particularly if a goshen ridge dock (with 3 downstream tb4 ports) is connected during post. Sometimes the maple ridge controller malfunctions, and tb devices connected to the bus aren’t detected In the preboot environment. Nvm31 has no such problem. The only issue with nvm31 is that some older alpine ridge (jhl6240) devices don’t hotplug properly, they need to be connected before booting the system (nvm36 rectifies this hotplug issue but introduces other issues).
