They sort of hang themselves with this -- gitlab runners will occasionally hang and just run for the full 1 hour max, making it very easy to max out your hours. Presumably they don't fix this so people max out their hours and have to buy more, but it also hurts the bottom line of their free tier. I see this happen at least 2x a month on our project, and it doesn't seem to correspond with any particular docker image.
And no, we don't do this on purpose in order to have you buy more minutes.
https://gitlab.com/gitlab-org/gitlab-runner/-/issues
Darren Eastman - Product Manager GitLab Runner