Ask HN: GitHub Actions free for Open Source: Unlimited Until ... ?

So, GitHub Actions (the built-in CI/CD tool) is currently free and unlimited for public repos.

I'm looking for any insight on how long this might last.

I'm finding this question hard to judge, because the offer clearly brings incredible value to Microsoft and GitHub, but the nature of Actions means their cost could add up quite quickly. Matrix tests can lead to exponential explosions of runner time, and I've seen repos that can easily rack up 10+ hours of runner time per push.

My own experiments with Actions currently take about 45 minutes of runner time per push, a good chunk of which is Mac runners, which are quite expensive on the paid private repo plans -- 8 cents per minute. (Though maybe this is explicitly subsidizing the public repos!)

Have any public repos been warned or had their Actions limited for aggressive (but not fraudulent) use?