Weird Start-Stop-Start Sequence of my Computer at Boot

Since a couple of days my Computer behaves weird at startup. When i switch it own it powers up for a couple of seconds, then shuts down and starts again and boots normally.

I haven’t changed any hardware, in the bios the linux-boot manager is set. i use system-d bootmanager.

I have no idea what causes the weird Start-Stop-Start Sequence. Could it be related to Linux / CachyOs (updates) or system-d?

Any ideas or recommendations for a fix?

It sounds like it’s fast booting to a missing/buggy boot manager, restarting, then booting normally to a different device or with safer settings.

Do you have fast boot / “show logo” / timer (whatever the BIOS calls it) enabled?

Does the issue present itself when manually choosing each option from the boot list to boot from?

Does this happen immediately after the PC is powered on, after POST, or when trying to boot an OS?

Thing happens before i get to see any boot info or the like; Fast Boot is not enabled …