Credit, or a warning?

Yes.

Initially it was giving me answer that glass is better, but when I asked for the sources it searched the internet and gave me that answer. I guess there is a lot of text (just general articles) about recycling and glass, saying one thing, but the actual studies published in journals show different picture, at least with PET.

In general, I found very helpful to ask the same question different ways and ask for the sources, otherwise it will give "common knowledge", which can be wrong, or misleading.