discucusted1212Your unit must have been defective, I've had mine for a few years now and it's great. I actually 3d printed a handle for it. I would probably order one for an xmas gift if they were shipping before xmas.
discucusted1212The stainless steel used in these WILL rust in contact with air or water that has above-average chlorine content.
You can read that as exposing the inside of the growler to salt-water or hanging around the sea or a properly chlorinated swimming pool.
I bought a 32oz KK from the Toronto MEC and I have used it only for cold filtered water in the office and the replacement stainless steel cap I bought for mine has some rust on the threads after almost two years but as far as i can tell with a high-CRI LED, the insides are still clean.
I ended up buying the KK because I had bought two HydroFlasks brand new from Amazon.ca but both failed the vacuum seal integrity test and were sent back.
The KK passed it with flying colors.
My Amazon review on my experiences with the two HydroFlask's has the test procedure at the end of the review, linked below:
https://www.amazon.ca/review/RVT1TOHO5PEDH/
HTH