I don’t hear any sound, although it will often trip when I am not here or when LOTS is going on. I just cannot imagine WHAT this could be:
That’s a fairly typical defroster heating element (fridge or freezer) cycle and wattage. Can you correlate it with the Main Power Meter and/or fridge/freezer detection.
BTW the little plateau at the end of the on cycle indicates a Sense averaging for the cycle.
While it appears like a defrost element as @ixu has pointed out, the wattage is much lower than my side by side, mini beverage fridge and small chest freezer.
Kinda depends on the fridge … my modern-ish Blomberg has a 150W element. Given the other indication, that it’s not being detected as part of a “normal” fridge, it may be like mine: an undetected inverter-based fridge.