I think this is because immigration is mostly pushed by people with heavy ideological reasons (far left, no border militants, etc.) but also rich employers who just want cheap and malleable workers.
Now you have the common people to whom you never asked their opinion about mass immigration: they now understand that instead of increasing wages, giving better benefits and improve working conditions to attract potential workers where it is lacking (supply and demand), the rich employers cheated the game with the help of elected politicians, by bringing hundreds of thousands of people who are willing to do it for less.
Add to this difficulties to buy a home, wages stagnation, rent going up, general inflation... The rich get richer, the rest gets poorer. This is how hatred is born unfortunately.
Now you have the common people to whom you never asked their opinion about mass immigration: they now understand that instead of increasing wages, giving better benefits and improve working conditions to attract potential workers where it is lacking (supply and demand), the rich employers cheated the game with the help of elected politicians, by bringing hundreds of thousands of people who are willing to do it for less.
Add to this difficulties to buy a home, wages stagnation, rent going up, general inflation... The rich get richer, the rest gets poorer. This is how hatred is born unfortunately.