in industry

I think, that is the important point here.
A private person letting Claude Code generate a spreadsheet behaving like Excel that they then uses to categorize their tea bag collection, is as far from any “industry” as possible.

But even if a Company is doing it… Say, they wrote their own chat app that behaves like MS Teams and use it internally… What are the potential allegations Microsoft could raise?

(One additional info: I’m an European, while your use of the legal term “fair use” tells me that you are likely from the US - in Europe there is no way to patent “business processes” like the behaviour of an interface…)