When we have had the daily coffee credit on some other ships, we received physical vouchers. However, as previously mentioned, a daily coffee credit was loaded on to our seapass cards on the recent Anthem TA.
What was odd, to us at least, was that the coffee posted on our account just like the drink "vouchers" for Diamond through Pinnacle. Even odder, we were in a suite, and the "free" drinks provided to suite guests in the concierge lounge on the Anthem also posted on our account like the D/D+/P vouchers. It took a bit of sorting to know which were our actual vouchers, and which were the additional "free" drinks.