GeForce NOW check for Steam does not collect, store, or transmit any personal data. There are no analytics, no tracking, and no accounts.

• Network requests: The extension makes a single kind of outbound request — it fetches NVIDIA's public GeForce NOW game catalog from games.geforce.com. No information about you, your browsing, or your Steam account is sent; the request asks only for the public list of supported games.
• Local storage: The fetched catalog is cached in your browser for up to 12 hours so it isn't refetched on every page. This cache never leaves your device and contains only NVIDIA's public catalog data.
• Page access: Content scripts run only on store.steampowered.com store and wishlist pages, where they read the Steam app IDs already on the page to look them up and draw a badge. Nothing else is read or transmitted.

The extension declares no data collection in its manifest. Questions: https://github.com/mjrossi/geforce-now-steam-check-firefox/issues