It's probably not illegal for advertisers to racially profile you, but it certainly is illegal in the US to do those things as part of your hiring process:

https://www.eeoc.gov/prohibited-employment-policiespractices

LinkedIn's scanning for browser extensions used by protected groups allows them to provide illegal services to US-based recruiters. I have no idea if they actually do it or not, and am not a lawyer, but common sense suggests there's enough here for a class action suit to move into discovery.