I would say that, unless it’s specifically stated that the vibe is bad, “a vibe” and “vibing” are terms with positive connotations.

So saying “the comments are a vibe” is like saying “I like how these comments make me feel”.

It’s something like the emotional atmosphere or something’s aura.

So a “vibe check” is evaluating how something makes you feel. If it makes you feel good, it passes.

the fact it’s spreading means that it’s perfectly adapted for survival in that environment you created, so it’s perfect for that pace.

There is such a thing as exotic invasive species that destabilize the local ecosystem, though.