It doesn't take much to ruin a joke, and it's a sure bet that once corporations get involved and try to get in on the joke that it's run its natural course as something that was organically cool and fun and has now entered the phase of its existence where it's co-opted to the point of losing its edge and meaning. You can almost set your watch to the time it takes for a meme to be born on the internet to the time that it ends up on some company's Twitter page in post trying to sell you something, even if it's just that the particular brand is hip and with it and definitely a fellow kid.
So it is with "OK boomer," a phrase once meant as insult and withering critique that now finds itself as subject of competing trademark claims by companies undoubtedly looking to cash in on its current popularity. As noted by NPR, the New York Times, and others, multiple companies have filed trademark applications on the phrase for purposes that might surprise or horrify were we not so inured to this sort of thing happening all the time with anything that becomes popular. Fox Media filed a trademark for the phrase with the aims of at least considering a TV show, presumably about young people yelling at baby boomers, one that would probably go unwatched by actual young people.
Fox is not alone in trying to get in on the action; the Times also notes applications from individuals and companies that would see the phrase used for clothing and apparel, stickers, and even a live stage show. And it seems certain that more will arise, if they haven't already; to let such an opportunity pass you by would be downright un-American.
The popularity and ubiquity of the phrase —the very thing that draws these companies and individuals like a moth to flame— is what presents a problem for those companies looking to cash in. As noted by trademark attorney Josh Gerben in the above NPR article, the phrase is so popular and so widely used that any applications to trademark it will almost certainly be rejected for lacking originality and uniqueness. That opens the door for it to be used by any and all, which is both a sign that our trademark system works and that we live in some dark times.