Webpagetests take longer time to run on multiple pages at a time.

I am conducting webpage tests on 3 web pages using GitHub actions. Sometimes, the webpagetests keeps wait in the queue and get cancel at the end. Usually, it takes only 5-10 minutes to run all webpagetests. Why does it keep waiting in the queue and eventually fail?
I have also shared screenshots of errors that are received while running the GitHub action.