It's fair use if you do it, it's stealing if someone else does it to you, this is the normal playbook of the likes of Meta, Microsoft, OpenAi and the others.
Did Microsoft say that OpenOffice/Libreoffice's interface was directly copyright infringement? I know people that could not make a distinction 10 years ago (now with the ribbons is simpler to distinguish).
Ofc Microsoft tried to limit the use of OpenOffice/LibreOffice using file format quirks and other strategies, so they are no angel, but still I don't know of a clear parallel.