@Abir Bhattacharyya Thanks for reaching out. It looks like there are dependency issues that would cause this behavior. Please review the Diagnose and solve problems blade on your function app after deploying your application. If you observe module not found error for the sqlalchemy then please verify whether you have specify it in your requirement.txt file for any package management.
In case if those module or dependencies cannot be installed using pip then you need to use build native dependencies or enable remote build.
You can refer to python troubleshooting document for more details.