The incident is resolved.

GitHub has now acknowledged that webhook is experiencing degraded performance, which is very likely to contribute to the incident.

We are continuing to monitor the situation.
https://www.githubstatus.com/incidents/d1stj7xcn4fy

the issue seem have been resolved by GitHub, queued jobs are now being started.

We start to observe a higher ratio of jobs not able to be started by Github Actions runner.

Github's recent status update only reflected an incident with Pull Request performance, GitHub Actions is still marked as Normal. We are closely monitoring the situation and will update when more information is available.