Yes, it's nice to see a study backing it of course but this has been intuitively obvious for a while. The "screen time is killing our kids!" crowd is just the latest generational re-incarnation of the "computer games are killing our kids" from the 1980s, or "Dungeons and Dragons is killing our kids!" from the late 70s through the 80s, "TV is killing our kids!"...right back to Socrates moaning about writing. Just another moral panic.
Since we're in 80s mode, let's quote The Karate Kid: "concentrate on quality of what you know, not quantity". It's the nature of the screen time that's important, not necessarily the raw bulk. Are you interacting with people online, are you reading stuff? Are you watching some videos where you learn some things as well as just the latest cat videos or TikTok dance? In short, are you using the screen as a portal to the generalities of life instead of just watching brainrot all day every day?
I suspect knowing that will be key to whether the screen time is hurting or helping. And as ever, a balance is required. 100% screen and no in-person interactions is obviously harmful, provably so thanks to the pandemic providing us with data here. I'd also posit that 100% outside and in-person will be good, but not as rounded as a decent mix between the two since you gain access to different experiences online.