Microsoftmsraj for logic apps that’s correct, unless you jump through some silly hoops to grab key vault secrets using a dedicated connector while ensuring secure inputs and outputs are configured for all the correct stages… in my opinion it should be natively supported, or at least the connectors using secret material should offer a secure storage method.
You’re definitely better off with the azure function method. You can leverage key vault secrets natively in environment variables. Check the process to do that here - https://docs.microsoft.com/azure/app-service/app-service-key-vault-references
