Italy was the best team in the last Euro. You can call that a miracle based on what happenned AFTER the Euro, but nobody had a doubt as to whether they were good enough during it. They outplayed everyone.
Greece and Portugal were fluke victories, yes.
Spain were among the favourites in both their victories.
All in all, in all of Euros in the 80s, 90s, 00s, 10s and 21, you had 3 teams winning that were not among the favourites :
Denmark 92, not even qualified. Played like champs, without pressure. But yeah not expected, but very not flukey.
Greece 04, outplayed in every game, defending well and hoping for a corner kick miracle.
Portugal 16, and even then they had a strong team. It's more of the way they played, and benefited from a new rule to even get out of their weak group. Also survived a miracle in the final. But again, quality team on paper that played like Greece 04.