Following advices I changed the power supply for a Seasonic Focus Prime PX-650:
https://www.kitguru.net/components/power-supplies/zardon/seasonic-focus-px-650-platinum-review
PSU changed on Saturday, 2 days later first BSOD:
System Information (local)
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Computer name: DESKTOP-L3V0LM6
Windows version: Windows 10 , 10.0, build: 19041
Windows dir: C:\WINDOWS
Hardware: ASRock, B450M Pro4
CPU: AuthenticAMD AMD Ryzen 5 3600 6-Core Processor AMD8664, level: 23
6 logical processors, active mask: 63
RAM: 34286051328 bytes (31.9GB)
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Crash Dump Analysis
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Crash dumps are enabled on your computer.
Crash dump directories:
C:\WINDOWS
C:\WINDOWS\Minidump
On Mon 20/07/2020 17:28:00 your computer crashed or a problem was reported
crash dump file: C:\WINDOWS\Minidump\072020-12968-01.dmp
This was probably caused by the following module: ntoskrnl.exe (nt+0x3DDB60)
Bugcheck code: 0xEF (0xFFFF9C0FC9DE2080, 0x0, 0x0, 0x0)
Error: CRITICAL_PROCESS_DIED
file path: C:\WINDOWS\system32\ntoskrnl.exe
product: Microsoft® Windows® Operating System
company: Microsoft Corporation
description: NT Kernel & System
Bug check description: This indicates that a critical system process died.
There is a possibility this problem was caused by a virus or other malware.
The crash took place in the Windows kernel. Possibly this problem is caused by another driver that cannot be identified at this time.
I'm running out of ideas here...
Any help would be super super appreciated!