Prerequisite Connect-AzureAd module should be installed if not already installed:

• Install-Module AzureAD

Connect-AzureAD -TenantId "<yourTenantID>";
New-AzureADServicePrincipal -AppId "7a24742e-0a1c-4225-844f-4d0948d515c4";

Currently Microsoft is changing the way they handle the API Access for SharePoint WebParts. When you receive an error during the approval process, you have to give the permission manually via the PowerShell script in the following section.

<#
.SYNOPSIS
This cmdlet privovides a way for developer and system administrators to add permissions to AAD protected APIs for SharePoint Framework custom code.

.PARAMETER appID
the ID of the app to set permissions for
.PARAMETER scope
the scope of the permission request to add

.EXAMPLE
AddSPFxPermissions -appID "00000003-0000-0000-c000-000000000000" -scope "Sites.Read.All"

.NOTES
requires Graph SDK to be installed. Follow documentation here: https://learn.microsoft.com/en-us/powershell/microsoftgraph/installation?view=graph-powershell-1.0
#>

[CmdletBinding()]
param(
    [Parameter(Mandatory=$true)]
    [string] $appID,

    [Parameter(Mandatory=$true)]
    [string] $scope,

    [Parameter(Mandatory=$true)]
    [string] $tenantId
)
# when the app is still not working use following sPFxAppID instead 6326b94e-cdee-4c5c-809b-00830522ca86
$sPFxAppID = "08e18876-6177-487e-b8b5-cf950c1e598c"
$objectGrant = $null

connect-MgGraph -scopes "Application.ReadWrite.All", "Directory.ReadWrite.All" -TenantId $tenantId -NoWelcome
try{
    #Get the SPFx Service Principal
    $sPFxSP =  Get-MgServicePrincipal -Filter "appid eq '$spfxAppID'"
    #get the endpoint service princpal (required to identify the object ID)
    $resourceSP =  Get-MgServicePrincipal -Filter "appid eq '$appID'"

    #check if some scopes have been already added for the endpoint
    $oGrants = Get-MgServicePrincipalOauth2PermissionGrant -ServicePrincipalId $sPFxSP.Id
    foreach ($item in $oGrants)
    {
        if( $item.ResourceId -eq $resourceSP.Id)
        {
            $objectGrant = $item
            break
        }
    }

    #if $objectGrant is not null, we check if the scope already exists there
    if ($null -ne $objectGrant)
    {
        if ($objectGrant.Scope | Select-String $scope -Quiet ){
            throw "Scope has already been granted"
        }
        #The scope was not added, added it to the $objectGrant and update it
        $objectGrant.Scope += " $scope"
        Update-MgOauth2PermissionGrant -OAuth2PermissionGrantId $objectGrant.Id -Scope $objectGrant.Scope -ErrorAction Stop | Out-Null
    }
    #otherwise, we just create the new object witht the scope 
    else{
        $params = @{
            "clientId" = $sPFxSP.id
            "ConsentType" = "AllPrincipals"
            "ResourceId" = $resourceSP.id
            "scope" = $scope
          }
        New-MgOauth2PermissionGrant -BodyParameter $params -ErrorAction Stop | Out-Null
    }
    
    Write-Host "Permissions set for SPFx app with ID $appID"
}
catch{
    Write-Host "the following error occurred: $_.Exception" -ForegroundColor Red
}
finally{
    Disconnect-MgGraph 
    Write-Host "Command completed."
}