Your code reads STRIPE_KEY. Your .env.example forgot it, and so did the repo's GitHub Secrets. You find out when the deploy fails.
keyparity checks that every environment variable your code uses is in .env.example and set as a GitHub secret, and flags the ones nothing uses. It reads secret names only, never values.
npx keyparity auditNew here? Look for issues labelled good first issue. Each one says which files to change and what "done" looks like.