That was the issue
Spoiler: show
In the end i downloaded ThrottleStop (Ver. 8.10) and disabled BD PROCHOT. Right after that CPU speeds went up to 4 GHZ
Long story short, bad sensor on motherboard telling my CPU that the processor is hot when its not, forcing the CPU to throttle down. Which fits the idea that shit just happened overnight.
Its fucking fixed. Thanks all for helping me through this.