Cooking sushi rice if done the right way its fine . What if you add the seasonings stuff eg the sushi vinegar etc into the pot of the rice cooker?
This can damage the non stick lining of the rice cook esp at the bottom (not the sides). U will see small areas of dark spots revealed when the non stick lining wares off.
Thus the correct way is to scoop out the rice (after is cooked ) into a wooden container which looks like a tub meant for the rice to be seasoned to get sushi rice.
If U do not have a wooden tub , use a big porcelain bowl / pyrex /corning ware
to place the rice for seasoning. as vinegar can react with metal, melamine ware, plastic.Overtime, these utensils surface will be discolored .
Similarly if you are making achar (Nonya ) using a kuali (wok) do not use a non stick wok to cook the vinegar solution. The wok suface will turn rusty looking after 1 use and its damage.....and U have to repalce a new one.
Solution: When cooking pickles stuff , always use a stainless steel wok . So far I find it okay to use it for preparing large amt of achar during Ch.new yr .