Documentation in the editor covers suggestions and code
I went to https://elm-editor.com/ and triggered the suggestions. This pops up and covers what I want to see:
Instead, the second (documentation) pop-up window should be to the right of the first one.
I tested it in the current versions of Firefox and Chrome.
Is there any way to reproduce this? I tested here with Chrome Version 95.0.4638.69, and it opened the details for the selected item to the right without covering the list. Here is a recording of the process:

I think the difference is that you have the text editor section maximized, while I did not. If I maximize it, it does behave correctly, like in your video.
However, in the default split-screen view (showing half text editor, half complied app), the popups stay contained in the text editor area, giving a bad user experience as they pile up and cover the code you are trying to write.
However, in the default split-screen view (showing half text editor, half complied app), the popups stay contained in the text editor area, giving a bad user experience as they pile up and cover the code you are trying to write.
Here is a screenshot of a test with the default layout, where the editor takes up the left half. The details popup appeared under the list:

The popup seems currently limited, at least to the iframe that contains the editor.
I am interested in seeing ideas on how to also use the space on the right side for these popups.