Important to note that the article says it can save to Onedrive or cloud drive of your choice. Its not clear exactly how that works if you want to save to Box, or Dropbox or something else but it looks like the option is there and it seems like you may even be able to turn that off if you want.
If it's still not your preference, I've seen licenses for office 2019 for sale on the web, which predates a lot of the cloud integration and AI tool nonsense. Between that and libre office there are ways to avoid using this service if you're so inclined.
What bothers me is that I'm getting all this "upgrade to windows 11" crap from other companies, like my antivirus. I get that eset reason to tell me about possible security risks to my computer, but I'd prefer if they give me options for addressing it that don't involve dealing with a new OS, especially the win 11 dumpster fire.