Vlad
I found a Apple guide that explains this feature:
In the Tab preferences, you can choose when new pages open in tabs instead of windows:
Never: if a link is meant to open in a new window, it will open in a new window.
Automatically: links meant to open in new windows will instead open in new tabs.
Always: links meant to open in new windows, even those coded to open in their own separate, specially-formatted windows, will instead open in tabs.
The Always settings puts specially-formatted windows in tabs instead of single tab windows.
For example, google uses these windows for users to Sign-In. And with the MacOS feature Stage Manager, when one of these Sign-In popups appear, it pushes my main Orion window out of the way.
Example of a specially-formatted windows:
