If it's too difficult to have Waze team fix the time zone issue, how about Waze telling the user the destination crosses a diff time zone and to display a warning that they should manually set the time zone on their phone to the actual destination time zone to prevent confusions/issues. That way, Waze won't adjust when crossing the zone and destination will display ETA correctly for the whole trip. At arrival, another warning could be to remind the user to set his time zone on phone back to "automatic".