It's got nothing to do with polarized cords. It's not designed to switch DC. You use it and it won't last very long.

​

How about something like this instead...

https://www.amazon.com/Grounded-Single-Adapter-outlet-indicator/dp/B07922QTLS/ref=asc\_df\_B07922QTLS/?tag=hyprod-20&linkCode=df0&hvadid=241980973821&hvpos=&hvnetw=g&hvrand=18228467148677500253&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9010194&hvtargid=pla-995939238695&psc=1