Assign GitHub issue to more than 1 people
Answer from Github:
With the recent updates, if you are using GitHub Free, then you will only be able to have a single assignee for issues or pull requests:
https://help.github.com/en/github/getting-started-with-github/faq-about-changes-to-githubs-plans#if-i-downgrade-from-github-team-or-a-legacy-plan-to-github-free-what-features-will-i-lose
As per the docs here for github.com, you still should be able to do it. I just checked on my android app and I am able to do it.
I have just verified in Web as well and I am able to assign to multiple people. I am also seeing the message "Assign up to 10 people to this issue".