Hi Chan,
From your post, I understand you have some security concern regarding Visa, Master card which support payment function in your app. Please note that Google Cloud is PCI security compliant, Protecting customers’ card information and ISO 27018 certified - Protecting personal data information. You can find more information in these documents[1][2].
Google Cloud products are in scope with many standards, certifications & regulations in different regions, continents. Here is detailed information[3]
Please let me know if above address your query?