In both Composition mode and in the regular editor, copying or cutting text that does not include the first character of a line, and then pasting it to a blank line, removes the hanging indent (as set by the sliders on the ruler).
“Paste & match style” works fine.
It’s not the same but could be related.
In the linked thread, the ruler indentation markers are both at zero. In mine, the top marker is at .5" and the bottom is at zero. Thus giving a hanging indent to any text. Every time you hit enter, it starts the next paragraph at .5.
However, like the video, its only the very beginning of the paste that ignores this indentation.
Pasting a copy/cut sentence results in removing the indent AND the line spacing.