This is probably my 10th batch and I've never had an issue with drinkability or infections, so i just want to make sure this is normal. I assume it's just Co2 bubbles, but i am not 100% sure. What else could it be? The Krausen falling maybe? I'd assume it's just bits of yeast and wort proteins or Co2 bubbles. Can anyone confirm this? Does it look insidious?
looks good, nothing to worry about
On the sides, that's just the yeast and other particles falling back in and getting hung up. I've noticed it on that style of carboy more than smooth wall styles. Also if using starsan with water with high minerals and it air drys leaving a surface that things can cling to.