Professional-strength acidic cleaner is intended for grout, not stainless steel; prolonged contact or residue could etch, discolor, or dull stainless steel, especially coated or finished surfaces.
Why
The manufacturer specifies white/tinted tile and bathroom grout and does not approve stainless steel. The product's acidic chemistry creates a credible damage mechanism, while direct stainless-steel compatibility is unverified.
What to do
Do not use as a general stainless-steel cleaner. If incidental contact occurs, rinse immediately and thoroughly, then dry. Do not use on coated or specialty-finish stainless steel without manufacturer approval.
pH
Acidic formula; numeric pH not provided.
Relevant chemistry
Professional-strength acidic grout cleaner and brightener.
Source: official product page ↗