In the README.md file, there is...

Common questions about this Template

1. Is this template Moodle as IaaS or PaaS? While the current template leverages PaaS services such as Redis, Azure Database for MySQL Flexible Server, Azure Database for Postgres, MS SQL etc. the current template offers Moodle as IaaS. Given limitations to Moodle our focus is IaaS for the time being however we would love to be informed of your experience running Moodle as PaaS on Azure (i.e. using Azure Container Service or Azure App Service).

What exactly is the limitations to Moodle on Azure App Service?