We have recently switched to GitHub actions and in addition to the above, there are two others which impact us:

Sometimes the checkout action fetches the wrong commit! The SHA in the GitHub environment variable says one commit, but the actual code is different(!). Because we don't know why this happens we basically need to do an unshallow fetch of the whole repo to be sure we have what we expect.

Using autoscaling self hosted runners, it is not currently possible to instruct the agent to finalise the current job but to accept none after it. This is essential to avoid broken workflows while scaling in. Gitlab supports this via a signal, but there is no equivalent.