I'm more concerned that whether intentional or not this will probably cause problems for users who use non-chrome browsers. Like say slowing down requests that don't have this header, responding with different content, etc.
User-agent discrimination is tolerable when it's Joe Webmaster doing it out of ignorance. It is not acceptable if it is being used by a company leveraging their dominant position in one market to gain an advantage over its competitors in another market. It's not acceptable even if it's not said company's expressed intent to do so but merely a "happy accident" that is getting "overlooked".
Indeed, even for those who require a round of mental gymnastics before they concede that monopolies are, like, "bad" or whatever, GP points out precisely how this would constitute "consumer harm".
Tell that to Google intentionally slowing down Firefox even without ad blocking. (I'm talking about them using the fallback for web components instead, not the slowdowns when ads don't load.)
