Germans would not even wave their own flag until recently when Germany won the world cup.

That was 2006. Not anymore. Merkel does not like it at all. And people blindly do what she says. If you don't, she will label you a "Nazi" or "Queerdenker" or "Antisemite" or similar.

There is a famous scene where she takes away the flag from some other politician, who is waving it on stage after winning some election. Not allowed.