Where a scraper is approved, a damaged or unsuitable blade can scratch the surface. It must be used only in the manner specified for that hob.
What the observation means
An ordinary craft knife is not the same tool. Printed areas and surrounding seals may have different restrictions from the main glass.
A useful next step
Check the owner's cleaning guidance before use and keep the tool away from children. Do not scrape cracked glass or increase force against a stubborn mark. Stop if the surface chips or the blade catches, and seek advice rather than continuing with a sharper improvised tool.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.