HP did release an updated BIOS image (F.24 Rev.A) for the 14-cm0072au but I am still getting the 15%/0.38GHz throttling issue.
Just wanted to add that I've got similar issues with an HP notebook 17-ca0992nd. When I shut down the laptop on AC-power, and then boot on battery, the CPU is locked at 0,38Ghz. The laptop has an Ryzen 2500u processor. Latest BIOS update from HP (F41 rev A from june 2019) does not fix this problem.
Oddly my other laptop (Lenovo Yoga 530) with Ryzen 2200u doesn't have this problem.
I had same issue with "AMD Ryzen 3 2300U with Radeon Vega Mobile Gfx, 2000 Mhz, 4 Core(s), 4 Logical Processor(s)". It happened many times over 2 or 3 days seriously affecting my work. The issue then 'fixed' itself yesterday 2020.01.08 I think when I rebooted whilst disconnected from mains power. Unfortunately I installed the latest BIOS and so did not isolate the cause(s) but it hasn't recurred thus far. I will continue to monitor..
Update: Upon unplug, throttles back immediately to 0.38GHz , screen dims (due to power settings I guess) then back up to 2.38 GHz when I run HP CPU stress test.
When plugged-in stress test gets up to max ~3.21GHz.
This would seem to be fairly reasonable behaviour but I don't know the specs. There are a lot of threads on this significant issue!..