Except what is the point in having a 'traffic light' system? What is the point the government having a green list of safe countries, and then withdrawing the most popular one with 4 days notice?
Personally, if Portugal is that bad it needs to go on the red list, it should be immediate, not with several days notice. Same with every other country.
The government is tracking numbers etc for all these countries so can give some notice that they are expecting this country or that country to drop down a level (amber to green etc) but not give a date. For countries going the other way, they could give some warning that a country may end up red/amber soon but the actual switch of bands should be immediate.