This time around, a usually reliable source talks about the Fold6’s battery, though it’s unclear which Fold6 this is about. Anyway, the leakster known as Ice Universe claims that the Galaxy Fold 6 will have a 4,400 mAh battery with support for 25W wired charging.
In a later reply to an X user, he also confirms this is “final”, so no more changes should occur from this point on in the development stage of the device.