Over simplified, because Romani are usually nomad, they live in moving settlements and don’t typically integrate much wherever they settle in. A lot of the hatred they receive also stems from these settlements being illegally set up in private/public property, as well as how they result in a lot of trash being dumped everywhere. There is also an issue with Romani criminality (stealing, damaging property, and sometimes there are even shootouts between different Romani families which result in casualties).

There is also a perceived notion that governments do not want to deal with these problems, which further fuels the hatred against the Romani as they’re seen as criminals who get away with everything.

The truth of course lies somewhere in the middle. Most Romani are not bad people if you take the time to know them, but there is definitely a lot of toxic cultural norms being perpetuated by leaders of many Romani families, which doesn’t help with clearing the stereotypes, and with very little to no integration between the Romani and the cultures they are in, it’s hard to get rid of the animosity.