I suggest you check the Virtual Network Gateway from the Azure Resources portal and to fix it.
This kind of issues might come, when the resource removal is not followed as per Microsoft recommendation.
Are you able to locate the Virtual Network Gateway under resources.azure.com portal something like below?
You can try a force Update the resource.
Under the right pane, click Edit and then click PUT to forcefully update. If the resource is stuck in a deletion or updating state, the operation helps to resolve the issue in most of the cases I see.
Try a deletion after the above step and see if it helps!
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