Why are all site pages shown as a frame?

Question

Google Chrome

I noticed such a chrome error today, maybe you also encountered such an error.

Absolutely on all sites, including this one, when you click on the context menu (right mouse button) - there are buttons "View frame code and reload frame" - What could be the matter? I did not install anything in chrome, in terms of plugins.
See screenshot

Answer 1

I don't think this is a mistake. Well, there is such a menu item, so what? Suppose there are several nested frames (frames), why not consider the page itself as the top (0-th) level frame and apply this clause to itself?

Answer 2

They are not shown as a frame. It's just that you (and everyone) have such an item in the menu.
The page itself is considered a "top-level frame", but that doesn't mean it's in an iframe.
You open the element tree and look at the structure.

Answer 3

This change was introduced in Chrome 83. Possibly related to the new tab grouping feature

Answer 4

I have such a thing appeared after the update, most interesting