Sanding between coats of water-based finish
sanding between coats should just be a light rub, usually it's less effort to use a hand block, or a sanding sponge than to lift a power tool,  you only need to remove the sheen, when the paint looks mostly dull that's enough rubbing.

Water based finishes can take considerable time to set, especially during cold or humid weather.  If you ignored the makers advice for suitable painting conditions you will have to wait longer than the label suggests for the paint to be hard enough to sand.