Nah it's about distinct visible changes in on-ice play that have converted into increased production ever since he got away from playing with Anderson and Newhook. That also does not mean I am "blaming" those guys or saying he had nothing to do with that line's performance or that he was a perfect player from day 1. It means Anderson is not that good and that Newhook is a winger and not a C, not a great line for a 19 y/o adjusting to the NHL, and a combo of a better spot and his own development is showing results now.
It's certainly possible that he takes a downturn and this will end up looking like a hot streak in hindsight, but it's hard to really see it that way as it's not like he's riding some sky high shooting percentage. Ever since he's been put on the top line he's been consistently helping them drive the play and making big impacts on both ends of the ice. He's given that line a boardplay/forecheck/cycle + playmaking element and they're playing all around very well over the past two or so months controlling play against opposing top lines. It's not like they're just shooting 20% as a group and getting shelled otherwise, he's a key part of why that line is controlling play and creating dangerous chances again.
I guess we'll see how the rest of the season/next few years go but KK/Galchenyuk don't have anything to do with what's going on now. They were drafted 5 and 11 years ago, their coaches are gone, the entire team is different and they're entirely different players with no link to Slafkovsky, it's just fandom anxiety to map this situation onto those guys. It doesn't even really make sense either as KK and Galchenyuk both looked much better than Slafkovsky as rookies but worse in their 2nd seasons than he does now. If you're not sold on him being a star yet that's fine, but just because there are still some rough edges and there will be ups and downs in the future doesn't mean the last 2 months are an outlier.