They market it as a pure sine power supply: https://eu.ecoflow.com/products/river-portable-power-station?variant=37254607863972#:~:text=The%20RIVER%20has%20pure

They market it as a pure sine power supply: https://eu.ecoflow.com/products/river-portable-power-station?variant=37254607863972#:~:text=The%20RIVER%20has%20pure%20sine%20wave%20AC%20output%20of%20600W https://eu.ecoflow.com/products/river-portable-power-station... Is there another appliance that I can test to see if that's the issue? I don't have an oscilloscope. Edit: I just tested powering it from a UPS: It's flickering more now and when it show the correct content it stays for a second more then when powering from the ecoflow. The monitor model is: BenQ GW2780-T.