Green oxide

I’ve been researching green/blue oxide on copper plumbing pipes
Ive read articles that say its not a concern and other that say it can be a sign of leaking or potential leaks, poor workmanship etc
Does anyone have a definitive answer?

It depends on the cause/source. You need to be able to recognize the difference between flux oxidation (failure to wipe off the excess flux after sweating the joint), from oxidation indicating potential leaking. The first is not an issue, the second may be.

Yes, it can be a leak or flux left behind…

Your job is to figure which.