I think with just the numbers presented it's hard to say if this is actually problematic. It's certainly a shift, but my teen half-sibling is hardly less social than I was at his age. He spends all of his time in discord with 'the boys', socializing on insta, or sending TikToks to girls he wants to flirt with from school. If anything I'd argue that style of teen life is hyper social compared to my time. And it's not like he can't meet physically with his friends or girls either, there's just not usually a reason to since with friends they have the most fun playing videogames and with girls there isn't much of a point unless it can be done outside parental supervision which happens but takes planning.