I have some bad news for you. Seems those Mercator Ikuu sockets are rebadged Tuya TS011F devices. They are notorious for switching off by themselves due to the built in over/under voltage protection.
There’s a huge thread over on Z2M github about this issue with no real solution unfortunately. You might want to try to check for firmware updates on your devices and/or calibrate the voltage, energy, current & power via Z2M just in case it helps.
I wouldn’t have high hopes though, so your best bet is to either return them or, at the very least, use them for non-critical devices.