I'm normally not a fan of comparisons with Nazi Germany, as that's the usual Godwin to use and it's almost always out of place.
But maybe here there is a workable comparison. In Nazi Germany, there was a lot of ostensibly good things: development, education, a feeling of belonging etc. And most citizens within Nazi Germany were normal folk who were, as you say, proud welcoming people.
But what Nazi Germany ultimately stood for was morally indefensible, it thus made the other bits very much faded into the background.
So today, if you're a German and you support Nazi Germany and/or fly an obvious Nazi symbol (the Hakenkreuz of which is legally banned) then you're being
fairly associated with the morally indefensible aspects of Nazi Germany.
And as
@Pittsburgh Footy said, today it's not much deeper than that.