Insecure content during the checkout process

[BouarfaMahi]

Hey, a few days ago, I encountered an issue during the checkout process of the Flask-based e-commerce app integrated with Stripe. I received the following error message in the Chrome Dev Tools:

'Mixed Content: The page at 'https://..../products/featured/' was loaded over HTTPS, but requested an insecure resource 'http://..../create-checkout-session/featured/'. This request has been blocked; the content must be served over HTTPS.'

I resolved this problem by adding the following meta tag to my HTML:

<meta http-equiv="Content-Security-Policy" content="upgrade-insecure-requests">

It's worth noting that I am using an HTTPS URL for the SERVER_ADDRESS variable. I do not understand what is happening.