A while ago I bought a roll of transparent petg "the filament" by spectrum. Wonderful, it printed great, shiny, smooth. I loved it.
Then I took advantage of the promotion on the Bambu lab website "4 rolls are discounted + free shipping" and I bought their transparent petg.
I opened the vacuum bag, loaded immediately in the printer and it strings and pops. Settings are correct as the slicer has a dedicated profile for this roll.
Their website says "warning: dry before using" - they mean that it comes already too moist from the factory?
PETG is very hygroscopic. It's one of those filaments that you should dry before using every time. Even if it's a freshly opened package.
Lol And here's me using two year old petg that was stored in open air on a boat without issues.
Maybe I just print slowly enough for that to be ok.
I've found it varies from manufacturer to manufacturer as well as colour, some of the petg I've got has been chilling in my cabinet in the garage for at least 1 summer and it prints fine, just some stringing, other spools they're a mess right out the bag. Still worth drying filament, but more so stuff like nylon which is extremely hygroscopic.
Print speed shouldn't really change anything when the filament is saturated with moisture. You might see more severe effects with faster printing but printing slowly with wet filament would still yield some pretty bad results. As stated in another comment, filament hygroscopy varies by brand so maybe you lucked out!
Slower tends to be worse as it gives the moisture more time to expand.