I've been dual-booting Linux and Windows for a while, with Windows as the fall-back option in case I wanted to use Office for something. Now that they tried to trick me into paying a subscription for their AI slop machine, I'm finally, fully out. It was a pain to actually track down and back-up the stuff that was held for ransom in OneDrive, but now it is done.
It can vary a lot depending the publisher, and some will not care at all while others will use, say, tracking features or work collaboratively (they can even be using OneDrive for that, which includes MS Office in its price), or they will require the author to use a specific Word template that they have devised for Word (with the person in charge of the final layout in whatever layout application, in order to streamline or the process and save time on that part of the job), when they aren't that kind of publishers that simply do the final layout directly in Word before sending the final PDF to the printer. Also, as an author, if a publisher has asked you to use MS Word and some specific stylesheet and realize they tried to to be smarter than them... good luck with that, unless they're already one of their best-selling author.
And that's just what comes to my mind and that I have been witnessing first hand ;)