https://wccftech.com/apple-just-stopped-signing-ios-15-0-1-downgrade-from-ios-15-0-2-no-longer-possible/

Apple has just stopped signing iOS 15.0.1 and iPadOS 15.0.1 updates for iPhone and iPad devices around the globe.

What this means is pretty straightforward, if you were thinking about jumping straight to that firmware, or downgrading from iOS 15.0.2 or iPadOS 15.0.2, then you can no longer do that.