Befuddle lists save result levels, but not save type.
Is it Will?
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As the book lacks the information, all we can do is guess what would make most sense, until we eventually get an official errata. Still, there is in my opinion enough reason to think the save would be Will that ruling it that way would not be controversial.
This spell has three tags: Emotion, Enchantment and Mental. All these three tags are associated with Will saves (including spells like Paralyze that could also reasonably have required a Fort save).
Flavor-wise, Befuddle is supposed to confuse your target's mind: why would that require anything but a Will save?
More recently Paizo officially errated this spell among other things from Lost Omens Gods & Magic:
Page 107: The befuddle spell is missing a saving throw entry. Before the spell's duration, add "Saving Throw Will."