SnowWolf said:
some people don't know the difference between breed and species. :|

That's for sure, unfortunatelly x.x
But I still think the difference is big enough to make a clear difference between what's hybrid and what's mixed breed. Especially with e621's tagging standards.

That said, I am not insisting on getting to use that very specific black_lab-dalmatian-mix tag again. A collecting term for tags like this, plus the original species/breeds would probably be the better solution to this. But I would ask for a few corrections on how it is at the moment.
Right now I have a bunch of former black_lab-dalmatian-mix tagged pictures that are tagged as hybrid now. And even if I would change them to mixed breed by hand I can't change hybrid on some cause black_lab-dalmatian-mix is locked to them.