There are several elements around this I think. I think that people have become very fed up with the way immigration has been done, and also to be sick of being told that makes them racists. That is around numbers, the economic role that they are filling, and the stress its placing on things like housing and health. I also think there is a class element in that there seems to be an uptick in the importation of other countries class and sectarian issues.
I think there is also increasing unhappiness with the way the refugee system works currently.
That does spill out in some cases into a general frustration with immigrants in the community, however, for the most part I think people draw a line between being unhappy with policies, or sometimes unhappy with the effect a community is having, and blaming that on individuals. The exception would be some of the refugees who some people suspect are not legitimate/honest.
Also, the increasing push from the progressive left to see people in terms of race, and to lump people together based on often pretty clunky racial profiles, has had the effect of making race something people are thinking about a lot more. Their idea is that this will be a positive thing, in fact, I think it's been quite the opposite, it's a gift to actual race essentialists. Nothing helps train people to be racists more than categorising everyone by race all the time.
At the same time, some have pushed back against that and been called racist for it.
So an increasing push to racialised thinking, coupled with a devaluation of the term racist because people think it is a bull shit accusation, it's not great.
That being said I think people in the UK are much less racist than most other places in the world.