The world conversion from 1.16.5 to 1.17 reset the custom generation setting to default.
The two level.dat attached come from the same world: one in 1.16.5, and the other one converted to 1.17
MC-228822
Generation setting reset after converting to 1.17
Resolved
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0
Since world generation data packs are experimental, you won't be able to use 1.16.5 worldgen data packs in 1.17, you need to use an updated datapack specifically made for 1.17.