@A1-IT-PC Thank you for reaching out to Microsoft Q&A, apologize for any inconvenience caused on this.
To test this behavior, we have created a sample user in our subscription and given contributor access at function app level only. Post that when we tried to log-in to portal with that user credentials, we are able to see the function app, enable and disable the functions inside the function app without any issues.
In your earlier response you have mentioned that you have assigned the user with contributor access and still user is not able to access/see the functions at which scope (either at function App level or resource group level or at subscription level) you have given contributor role?
Once a particular role is assigned to user it will take some time to propagate the access to the user. Can you ask the specific user to try signing-out and sign-in again and check.
Also, could you please ask the user to run this cmdlet in your local PowerShell or in cloud shell Get-AzRoleAssignment -ObjectId "<UserObjectId>"
to see what permissions has been assigned to him.
If you are still facing the issue, please send an email with subject line “Attn:Venkatesh|thread title” to AzCommunity@microsoft.com referencing this thread with the above cmdlet output as well, I will follow-up with you.