Maybe it's time to check for possible hardware issues since you log seems normal.
First check the disk drives, RAM and then the processor.
done already in the beginning, changed SSD, RAM and Power supply, only MB with CPU not.
But I can use this PC with Xeon CPU over days running 24/7, even CPU mining XMonero withhout any problem.
Also funny that this problem has only occured since and with BitcoinCore v0.21.0 or above... and only with Nicehash incoming transactions, others are fine