Sharing a small extension I put together to highlight YC Alumni usernames in orange for us (non-alumni) regular folks[0] - it's not auto-updating and I suspect very incomplete due to the source of data I use ("Show HN" posts on the /launches[1] pages, which only go back to 2017).
I'm aware a more fleshed out version might listen for newly posted "Show HN" posts or allow customizations, but I wanted to keep this simple for the time being.
[0]https://news.ycombinator.com/newsfaq.html >HN gives three features to YC: job ads (see above) and startup launches get placed on the front page, and YC founder names are displayed to other YC alumni in orange.