It's because they're joined by us anti-crime people against the Islamic fascism that's increasingly taking over parts of western towns and countries, and that cause is historically unbiased politically, as no one has ever benefitted from an Islamic influx.
When demonstrations against unprecedented mass immigration, and for National secular sovereignty appear, they get the "far right" headline. According to that, half of Germany is far right.
The Jew-hating thing that the far-right has always been known for, just like the left is now, seems to be in the background. No Synagogue or Jewish gathering in sports, funerals or commemoration of WW2 victims are in danger and guarded by police or military bc of Nazis.
Atm the entire right is preoccupied with the most immediate threat - those who are still actively hunting Jews in the west as well - Islamists.
Islam never stopped its religiously based horrors. And no, Jews never thrived in a Muslim Majority country - no one has or do . and "do" is the most important.
The closest you get to any kind of harmony is having another religion being dominant and be immensely smart or even slightly dictatorial about Muslims
These reasons. I started out with open border mentality. Then Muslims wrote critical pieces of their communities, that made the radicalism way more common, so I became cautious. Then this happened (first 3 are the best):
Having gone from Communism to Liberalism, to now center right has been a 10 year journey for me, while seeing the U.S Democrats going the exact opposite. Before the fall of the USSR and DDR, it wasn't a partisan thing to avoid Islamism - it was a world standard. Back when history was respected instead of changed.
the Social Democrats of my country have clammed down very hard on it, with the support of most of the left as well (combined 80% of the country support)