It is not an overheating issue. The Ps5 doesn't even feel warm to the touch, there is cold air blowing out of the vents and it gets cleaned regularly. If it was, the system would warn you that it is hot and will turn off.

It shuts off, without warning, and will not switch on again unless it is disconnected from it's power outlet and reconnected.

Contrary to belief, I don't think it's a software issue either. Various updates have been applied throughout the consoles history, not to mention the fact that not everyone has this issue.

So, it's likely that it's actually a hardware problem, I don't know specifically which piece is the issue, but it could be a faulty PSU. Remember these things are mass produced, and if there is a fault in their production lines, it can go unnoticed for a very long time.