It looks[1] like github actions only run on amd64 hosts, so if you use a platform matrix like in this example[2] I am fairly certain it is running under qemu just based on the fact that is takes roughly 10 times longer to run. I am aware of Blaze[3] has arm64 runners.

If you are willing to pay for it, you can also setup a runner that uses AWS Graviton EC2 instances[4], we do that at my workplace for our multi architecture builds.

1: https://docs.github.com/en/actions/using-github-hosted-runne...

2: https://docs.docker.com/build/ci/github-actions/multi-platfo...

3: https://www.runblaze.dev/

4: https://aws.amazon.com/ec2/graviton/