I have relatives in Finland, which historically has also been welcoming to immigrants. But last visit (2017), some of the family complained along almost exactly the same lines you describe. In recent times, they said, more of the immigrants seem no longer willing to even meet part way on assimilation. They are happy to take advantage of the social democratic nation the Finns have created, while also pushing forward their own cultural behaviors which are in some contexts in significant conflict with Finnish cultural behaviors.

Any given system - such as a "nation" - has limits on its ability to adapt. Push too hard and the system will push back, or collapse. Anti-immigrant/nationalistic behavior is one symptom of pushing too hard on such limits.