I used to use a lid on all the food I microwaved but I learned recently that microwaves and plastic are not a good mix. Low power with my inverter microwave has rescued the device as something useful for heating food!
By the way, the “inverter technology” isn’t really anything special. It’s a switched-mode power supply like you’ll find in millions of devices. The main difference is that this one can output the high voltages needed to drive the magnetron. It’s also a lot lighter in weight since it uses a much smaller transformer!