DHH wrote a blog post complaining about how there are fewer "native Brits" in London, and then linked to Wikipedia's article about the number of white people in London. He also brought up a march by Tommy Robinson, but framed it as just a couple of exceeding normal guys out for a walk, and not a bunch of nationalists.

It came off as xenophobic and racist, so sponsors pulled funding while others (some quite high profile) refuse to work with DHH. There's a non-zero amount of reading between the lines, so here's the blog post so everyone can decide for themselves:

https://world.hey.com/dhh/as-i-remember-london-e7d38e64

Why not read the source and decide for yourself? Here's a blog post linked in the article, as a start: https://world.hey.com/dhh/as-i-remember-london-e7d38e64