webapp:Get-AzResource lookup on Azure App Service does not return accurate NetFrameworkVersion

When assigning a variable to this:

$enumAppService = Get-AzResource -ResourceGroupName $resName -ResourceType Microsoft.Web/sites/config -ResourceName $website.Name -ApiVersion 2018-02-01

And then writing to screen like this:
Write-host $enumAppService.Properties.NetFrameworkVersion

The output is always v4.0 (this may align to what is seen via resource.azure.com). However, this is inaccurate as a view of the resource on Azure Portal reflects the right version (e.g. v4.5). Also, when using the more recent "-ApiVersion 2019-04-01" as part of the variable the issue is not resolved.

Please advise and correct this as appropriate.

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Get-Module

ModuleType Version Name ExportedCommands
---------- ------- ---- ----------------
Script 1.6.0 Az.Accounts {Add-AzEnvironment, Clear-AzContext, Clear-AzDefault, Connect-AzAccount...}
Script 1.6.0 Az.Resources {Add-AzADGroupMember, Export-AzResourceGroup, Get-AzADAppCredential, Get-AzADApplication...}
Script 1.3.0 Az.Websites {Edit-AzWebAppBackupConfiguration, Enter-AzWebAppContainerPSSession, Get-AzAppServicePlan, Get-AzAppServicePlanMetric...}
Script 1.0.0.0 ISE {Get-IseSnippet, Import-IseSnippet, New-IseSnippet}
Manifest 3.1.0.0 Microsoft.PowerShell.Management {Add-Computer, Add-Content, Checkpoint-Computer, Clear-Content...}
Manifest 3.0.0.0 Microsoft.PowerShell.Security {ConvertFrom-SecureString, ConvertTo-SecureString, Get-Acl, Get-AuthenticodeSignature...}
Manifest 3.1.0.0 Microsoft.PowerShell.Utility {Add-Member, Add-Type, Clear-Variable, Compare-Object...}
Manifest 3.0.0.0 Microsoft.WSMan.Management {Connect-WSMan, Disable-WSManCredSSP, Disconnect-WSMan, Enable-WSManCredSSP...}