I have had a few large format Lion and Lipo's that have had a gas build up under the outer plastic wrap and cause it to look puffed but they really are not. I dismantled one of the power pack batteries that looked this way even with a thicker plastic cover attached. Once I exposed the flat packs, they were not puffed at all, in fact, they look completely normal and were still at their factory thickness with no puffing at all! I also have a couple of drone batteries (Larger Drones) that have this same effect but when you glide your finger down the plastic wrap of the outer battery area that does not have a heavy plastic casing the puffed plastic is just gas trapped under this plastic and again there is no real puffing. I have had real puffed batteries before and the surface is much harder and cannot be pushed down easily.
Is this gas venting other's have seen before?
Is this gas venting other's have seen before?