Is it beneficial to publish papers from previous labs during grad school?
I struggle to see how having papers outside of your PhD field could be a negative - demonstrating you have knowledge, interest and expertise in a range of subjects can be a bonus. But as mentioned above, they must be of a standard you are happy to publish. Your PhD thesis (plus papers published along the way) will show your expertise in your main field, so why not show off your other skills too?

Plus, I imagine a lot of time and money has been invested into your previous work. I think you should use that for the benefit of your co-authors as well as yourself. But if you find the extra work is having a negative impact on your current studies, prioritise what is right for you.