Because the Government released restrictions for those days, many chose to visit relatives / old friends / have family gatherings ...
Our hospitals got overwhelmed, hence the ambulances waiting outside: IIRC, there were 46 ambulances with patients waiting outside a single hospital (our biggest) and the waiting time exceeded 10 hours for some of them ... no wonder the daily fatalities skyrocketed so much ...
As of today, Portugal has had 17895 fatalities attributed to COVID and, according to Worldometer, that's 1761 fatalities per 1M people: that's the equivalent of 562500 deaths, when roughly scaled to USA's population.
Portugal Coronavirus update with statistics and graphs: total and new cases, deaths per day, mortality and recovery rates, current active cases, recoveries, trends and timeline.
www.worldometers.info