In addition to what @ovidiubica said, check the individual product configuration and make sure you didn’t force enable test mode for that product.
If this is for a subscription product, then go through each of the following checklist items and check them one by one to make sure all the setup is correct. Then do a new test transaction after that.
Checklist #1) If you have changed between “live” and “test” mode, then make sure to create a new subscription plan in the mode that you are currently using and then use that plan to create a new subscription product.
Checklist #2) Go to the settings menu of the Stripe payments plugin and check the API key section. Make sure to copy and paste all the CORRECT API keys in those 4 API key fields. To be more specific, the following 4 fields must contain valid values:
– Live Stripe Publishable Key
– Live Stripe Secret Key
– Test Stripe Publishable Key
– Test Stripe Secret Key
Checklist #3) Go to the “Subscriptions” tab in the settings menu of the plugin. Check that the webhooks are setup correctly. Both the live and test webhooks should be setup. If in doubt, do the following steps to set them up correctly:
– Click the “Delete Webhooks” button.
– Click the “Clear Cache” button to clear any webhooks cache.
– Click the “Create Webhook” button in the “Live Webhook Status” section and wait for the addon to automatically create it for you.
– Do the same for “Test Webhook Status” section.
– Click “Save Changes”.