Happy to report that washing with PBW did not destroy my PEI sticker plate surface, it did clean a lot of grime, which i think mostly was the dishwashing detergent, i assume also pulled out some proteins not cleaned by the dish detergent from the micro surface of the plate.
Will post what i find when trying out a more fiddly print with smaller detail, but for now seems like ok option.
If you are going to now do this, try it with care, i have only washed my plate once with this so far and cannot report on longevity of the plate.
… dawn and fairy are IN MY OPINION still very viable and safe, just not maybe the best that can be