Not individual sh%, OI Sh% as in the percentage of shots that go in when he's on the ice, period.
12.5 individually isn't anything crazy and it isn't anything he hasn't done before (it wouldn't even be his career high.) That's probably sustainable to a certain degree and even if it holds all year and then falls back a bit after that, there isn't going to be a dramatic drop off there.
He's at 14+ all situations and nearly 11% 5v5 in on ice sh%. That is what won't hold.
Both numbers would dwarf what Panarin did last year (in a 120 pt season where he also shot the lights out) and his current all situations sh% would be his career high by like 5%. Theres no way thats his new norm because that would make him the best player in the league.
This is basically every Byfield heater ever where the overall numbers are pretty good or very good most of the time but the actual production jumps when other people around him get really hot. He'll fall back to earth and his tire pumpers will grow silent while his haters will take every opportunity to shit on him when the reality is that he's still the same guy he's always been. Analytically he isn't really a whole lot better than he was with the Rangers this year and certainly not better than he was before Chytil missed some time and that line was cooking everyone.
Higher TOI and PP1 minutes will make a difference and I don't doubt that getting a fresh start has helped him mentally too, but he didn't just go from a solid player to a star because he got the chance. He's been good, but it's luck driven too.