This rumor comes from a tweet that was posted on Capcom's official Twitter account on Valentine's Day. The rather ominous post features a countdown clock against a stark black background, seems to allude to a major impending announcement.
— Capcom USA (@CapcomUSA_) February 14, 2022
One twitter account in particular (@chinnerdomain) gave an example of the "evidence."
— Chinner (@Chinnerdomain) February 14, 2022
Whether any of this can be taken seriously though, is another matter. All of this information could be fake, for all we know. And this doesn't seem to be the first time rumors of Microsoft buying Capcom have surfaced, as a Destructoid post from around 15 years ago shows. It's not even clear whether or not such an acquisition would be legally permitted under Japanese law. At any rate, we will have to wait until Sunday to see if there is anything to the rumor or it's just fluff.