So I have tried now for 20h without Afterburner running. I updated HWInfo from 6.24-4120 to 6.26-4160 and here is the same readings. It might be worth noting that my Gigabyte X570 does not have this problem, only the Taichi.
Can you please verify with some other tool if it shows such erratic values too? For example CPUID HWMonitor or something else that shows min/max values as that's the best way to catch such out of range values.
I'm not sure. This would be usually a case when some other monitoring application is causing a conflict accessing the sensor. But if you're sure there's nothing else running...
A bad sensor would be quite unlikely, but I have no other ideas what could be causing this.
I had another thought based on your question about other monitoring programs. The Taichi has two 7-segment displays onboard for diagnostics and I had configured the bios to show Tdie temp on those. All readings have been normal for almost 24h after disabling that monitoring. Maybe that was causing the collision