Cannot change authsetting of Web Apps with new Authentication feature enabled from Azure Resource Explorer

I am trying to change additionalLoginParams of authsetting in Web Apps with new Authentication feature enabled, as shown in the image below.

But when I clicked PUT to save the change, it fails with an error shown in the image below. Does this mean I have to use a legacy one in order to change authsetting from Azure Resource Explorer, or is there any other place to change the setting for new version?

I can also reproduce your issue, as per Updating the configuration version:

Migration to V2 will disable management of the App Service Authentication / Authorization feature for your application through some clients, such as its existing experience in the Azure portal, Azure CLI, and Azure PowerShell. This cannot be reversed.

Even it does not mention Resource Explorer, but it should also be included, because when you set the authsettings with Azure CLI or Azure PowerShell, they essentially calls the REST API to do that, which the same as the Resource Explorer does.

Since this cannot be reversed, so if you want to set the additionalLoginParams, your option is to create a new web app, configure the auth in Authentication (classic) blade in the portal first, then set additionalLoginParams in Resource Explorer, at last upgrade it to V2, it will work fine.