[PROBLEM] System freezes after a while

[rph-r]

I doubt µSD is in cause. It is a Sandisk 16Gb.
According to these threads, it could be a power issue. Since the Pi4 is plugged on the Audiophonic card, I'm not sure I can do something. The 7.5A power supply has enough power, but I don't know how the circuit feeds the Pi, I'll check that.
At least it could explain why it is happening only when touchscreen is connected, but not really for the network.