Disable credit card and payment method syncing across devices

Firefox Sync lets you access data such as Bookmarks, History, Logins and Passwords, and Credit cards on other devices where you sign in with your Firefox accounts. To disable sync for sensitive data like credit cards and prevent purchases on a shared device, follow the steps below:

1. Click the menu button.
2. Click Settings.
3. Click Sync in the options to the left.
4. In these settings, you can choose what items to sync across devices where you logged in with your Firefox account.
5. If syncing is ON, then you're syncing the items that appear in the panel.
6. Click Change to open the Sync settings.
7. Uncheck the box next to Credit cards to stop syncing credit cards across devices.
8. Click Save changes.

Additionally, you can disable credit card autofill to prevent Firefox from filling in your credit card information on the device where your credit card information is saved.