Apparently when the connection is lost, you lose the progress (part of or all of the progress made), id est i was on a map and got disconnected, when finally was able to log in again my total minutes on the map (required for the daily quest) were back to 0, like i never played the map. This apply to dack changes too (like adding or removing cards from the deck and probably to other things too)
p.s. one of the hint (during the loading before the map start) still say something like "EA operators will never ask you for email or password", it's not an error but maybe doesn't really have sense