Mi7 - checkout recurring and one time prices

[vivid night]

You cannot include mode twice like that, but you can do this generally speaking

You'll want to use mode=subscription to manage the creation of the subscription as the foundation of the checkout session

Then the one time price can also be included in the line_items, and it will appear on the first invoice only

https://stripe.com/docs/api/checkout/sessions/create#create_checkout_session-line_items

For subscription mode, there is a maximum of 20 line items with recurring Prices and 20 line items with one-time Prices. Line items with one-time Prices will be on the initial invoice only.

So in your code, you need to merge those two line_items array into one, and just use subscription mode

Mi7 - checkout recurring and one time prices