What is AMD Prochot?
BD prochot is something that underclocks the CPU when temps are too high to help run the CPU in safe environment. It is recommended not to disable it as you might get high temps and high clock speeds which will ultimately burn your CPU.
What software are you using to read the temps? , which temp are you reading as not hitting 70°C? There are multiple temps associated with the cpu. The igpu is an almost seperate entity to the cpu, so if you are reading the wrong temp, the cpu could be running 60°C and the igpu could be running 90°C, but the temp at the particular reader could be seeing a radiated or averaged temp of 90°C, which is common for Ryzen Master as it averages the temps over a 3 second period.
It also doesn't help that temps are subject to actual time read. If the reader is reading every 500ms, and the temps are spiking 'off-read' you could very well see 50-90-60-90 etc and RM is averaging 50 and 60, but not including the 2x 90° peaks.
The only way to accurately assess temps is with a graph, not a readout, and every 256ms, and look to see what the peaks are hitting at and how often. It'd be very easy to see 90°C peaks, or higher, and still have the socket register 70°C, but have the cpu downclock anyway.