The entire article and "report" are so aggressive that it makes it difficult to extract any nuance out of it other than that I should use Brave. Is the core issue that council websites are using real-time bidding for their ads? Is this specific to the UK?
Yes. These websites are used to support a variety of public services, e.g. disability, poverty, drugs, or alcoholism services.
Brave believes that sending tracking information about people accessing this information is a breach of privacy.