The subjective experience I and others report is that GitHub feels to have gotten significantly worse over the last few months. If you look at the month over month view of "Uptime history" in the cited link[1], it confirms this: it's been sub-90 (even sub-80 last month) essentially since the start of this year (i.e. when GitHub says that commit activity 10xed). Go back even a year and it's all in the high 9s.

I honestly can't explain the discrepancy between the graph in the article and the month over month stats on the same page, but the latter tracks both to my own subjective experience of GitHub and their own internal metrics.

[1]: https://mrshu.github.io/github-statuses/