So I've had one of these for around 7-8 months. At the beginning, it seemed to work well enough. Recently, my wife started to get notifications that she was being followed by an unknown tracker. It was, of course, the card in my wallet, despite the fact that I (and my phone) were right there along with it. It would repeatedly lose its connection with my phone, for whatever reason, resulting in a bunch of notifications for both me and whomever I was with.
Not sure if it's the battery (non-replaceable) in the Chipolo card going bad or what, but I've dumped it for an Apple AirTag and replaced my wallet with one that has a little AirTag pocket as many now do.