You ought to try one of these if you want 24/7 voltage monitoring if you're comfortable with removing an outlet. AC Display Meter
https://www.amazon.com/DROK-Frequency-Electric-Voltmeter-Multimeter/dp/B07YC1XHKQ/ref=mp_s_a_1_14?dchild=1&keywords=power+meter&qid=1614886098&sr=8-14