I think we can see to Hacktoberfest as a comparison to this "let external junior devs to deal with backlog" idea. And this project gives the same fear and worries of that "chase for the cheapest PR to get my reward"-logic as that which Hacktoberfest encourages.

While GitStart pays their developers, that alone could encourage better habits, I fear it could also enable this chasing reward mentality harder, setting the juniors up for failure, as well as frustrating the customer with having to deny and review multiple low-quailty PRs.

How is this avoided? This seems heavily at risk to cause more headache than help.