It's remarkably much work to discover the significant and relevant contributions someone did to OSS just from their github profile. Lots of people have forked millions of well known projects. No interviewer has time to go through all of them to find the ones that were forked for good reason, i.e. to make amazing PRs and not just to fool around a bit.

Also, the contributions graphic (with the colored boxes) is often off-putting, because many people tend to also use GH for random weekend hacks, which are shown as "contributions" just as much as "oh I made Firefox 2x faster on BSD" kind of things are. To GitHub, a commit is just a commit, and "I ran create-react-app" and "Fixed impossible 10 year old race condition in Hadoop" are both shown as a green box.

Spell out your relevant OSS contributions in your CV and/or your email. Don't just link to your GitHub profile, GitHub profiles are shit.

To be honest, if you only link to your GH and then conclude that interviewers aren't interested in your open source work, then this gives me the idea that you're not that interested in your interviewers either. Help them out a bit!

I interviewed at three companies over the course of a few weeks once, not one asked me about anything on my GitHub profile nor about my blog (200+ technical articles). I was a bit miffed. At the last one I asked to see the CV they’d been given; the recruiter had removed those links from my CV. (This was in Austria.) So had I worked on open-source or blogged solely to get a job, it would have been a complete waste of time.

Overwhelming majority of people have no contributions or only small ones. Most people github profiles are a bunch of plat projects.

The companies won't hunt on github.

I don't think it does all that much difference even if they know about said contributions.