In PowerApps, connections to other systems are often a big issue and you don't want to store passwords or certificates in your code. This is where Azure Key Vault comes into play. Hat Full Of Data shows in their video how a secure solution can be built.
Hat Full Of Data "In this video I walk through connecting a flow to Azure Key Vault to fetch a secret value and how to fix the connection. Once that is fixed we then secure the secret in the flow action."