That seems pretty fine to me. The cellular radio must consume power to remain connected to the cellular network. Depending on signal conditions, it could use more or less. 20% (96 - 76 = 20, not 25) in 1 day and 16 hours seems pretty good to me. That translates to 8 days and 8 hours.
And considering that that is a 4xl, its also getting pretty old as far as lithium batteries are concerned, so I wouldn't expect the battery to have anywhere close to its original capacity.