Huh? Are you just looking at his stats without the context of how much lower scoring the KHL is? Where he ranked on his team each season:
2017-18 playoffs: 2nd in goals, 3rd in points
2018-19 season: 4th in goals, 3rd in points
2018-19 playoffs: 6th in goals, 1st in points
2019-20 season: 15th in goals, 24th in points (only 11GP)
2019-20 playoffs: did not qualify
2020-21 season: 1st in goals, 7th in points
2021-20 playoffs: 1st in goals, 1st in points
2021-22 season: 8th in goals, 12th in points (only 19GP, 4th in G/GP 6th in P/GP)
2021-22 playoffs: 1st in goals, 2nd in points
He's been a top 6 producer in the KHL since before he was even drafted.