1. Bayern just bought him last summer, so it would be 1 year of limited PT, not two.
Plus he's been a bit of a victim of Sabitzer's weird Bayern tenure. If Marcel had struggled as much this season as he did last season, then Gravenberch would've seen a lot of the ~1000 minutes that Nagelsmann gave to Sabitzer this season.
But since Sabitzer finally settled in, the young dutchmen fell to 4th or 5th choice in the midfield. Won't be surprised if Gravenberch has a similarly much improved second season at FCB.
2. He only missed time for Ajax at the end because of fitness, a bout of corona in the winter an injury to his knee at the end of the season. He played the full 90 in 7 straight matches before hurting his knee.