Bought a ring second hand as I prefer to keep products in the loop instead of always buying new ones. The ring was around 9 months old when I got it and it worked great - but after around 2 weeks it suddenly stopped tracking data and the battery went from 4-5 days to 15 hours with a full charge.
I contacted support, they asked me to perform a bunch of steps, record battery usage over 2 days, do factory resets, etc. At some point they told me they will send me a new ring. But once they learned that I got the ring second hand they suddenly refused to send a replacement because its "against their company policies".

Thats btw. the same company that highlights sustainability with their ring sizing kit, where they even ask you inside the packaging to hand it over to someone else after you used it to keep it in the loop. But when it comes to their rings they actively act against this. Such a shame and disappointment.