How to load VK comments widget in iframe?

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The domain and the widget are not mine, but they need to be loaded on my page.
If you just type the address into the address bar, everything opens, and in the iframe it says Invalid application domain.
In the anonymizer, for example, it loads after all ...
An example of a widget is here
https://vk.com/widget_comments.php?app=2877201&wid... Follow
the link, the transition is also Invalid application domain, press ENTER in the address bar, then it will be displayed