I have first-hand experience of the "vertical issue".
So, one day as I was playing Metro Exodus, PS5 shuts down abruptly. I restart, then after some time the same thing. This recurred for some time, then one day, as I was telling my friend this, he mentioned the vertical issue and advised me to place it horizontally. I did so. Lo and behold! The issue has not occurred since then.
Conclusion: The issue is real and exists. After some time, something happens that results in the liquid metal receding ever so slightly from the CPU surface.