@mushamajay-0860 Apologies for delayed response on this. It seems to be a known issue when using cmdlets that call the Graph API while authenticated with a service principal. Please refer to below threads and see if that helps
https://stackoverflow.com/questions/35592847/get-azurermroleassignment-access-denied-to-the-specified-api-version
https://github.com/Azure/azure-powershell/issues/1896
Please revert back if your scenario is not fitting the above examples and provide some additional details for your scenario with the steps being taken so that we can try to repro the issue and troubleshoot further. Thank you