Husso became a Jr.A (U20) champion last season and had good stats, perhaps playing behind a strong defence made him look better and more promising than he really was. Now that the conditions around him are different, there are more people questioning his talent and upside.
Another thing might of course be that not enough has happened with him, simply not enough development. Juuse Saros has emerged as the top 95-born goalie in Finland, and he's making everyone else (not just Husso) look substandard on most nights. Saros is now the obvious starting netminder for the U18 national team.
You might also say that Husso has some consistency issues. He had 7 shutouts this season which was the most in the league, but on the other hand there were plenty of games where he allowed several soft goals and looked bad. I'm poor with goalies, but things like focus, anticipation, and ability to react and act accordingly could’ve perhaps been better in some situations.