Electrical outlets go dark and then come back on their own
This is a fairly common failure usually seen when backstabs are used. Backstabs are the push in connectors when under heavy load they can open up and sometimes later they reconnect.
This also happens with loose wires in wire nuts and even broken wires.
The loose connection heats up moves apart and the circuit is dead , after cooling down or some vibration it reconnects until a load is on the circuit.
If you want to find the source of the failure but a plug in heater or hair dryer on it and turn it on this will usually open the circuit.
Why the circuit is not complete test each receptacle or device until you find the last working one or first non working one in that circuit. The problem will be at one of those 2 places 98% of the time. If you pull the receptacle out and don’t find a problem and turn the power back on and it works if it was back stabbed that is usually the bad one and you need to replace the receptacle or move the wires to the screws.