TBF not all are acting like useful idiots. There has been demonstrations near Russian embassies across Europe protesting Russia's military invasion of Ukraine - for example in Latvia, Lithuania, Poland and Finland.If they organize any demonstrations, they will take the line of "EU/US Hands of Ukraine" or some such, not "Russia out of Ukraine." If they try to organize such a demonstration (and I expect that they will), virtually nobody will show, because nobody else agrees with that nonsense.
Usually I'm not into Hitler caricatures - except when they're apt. Appeasement can only go so far as learned with Sudetenland.
Citites have also lit buildings in Ukrainian blue and yellow to show solidarity. Arad city hall in Romania:
Palace of Culture and Science in Warsaw:
In Sofia they famously love to paint the horrible Red Army monument with often humorous themes, but now its carrying Ukrainian colours:
Of course, it doesn't change much but I like it.