Had my Forerunner since 2022, no problems. I have the parkrun barcode widget and the TrainasOne app installed, both since 2022 also. I don't keep it connected to my phone; I sync it only after activities, so between 4 and 6 times a week.
It discharged totally from about 30% overnight two days ago, having done a bunch of activity tracking fine during the day, and then been connected briefly. I charged it to full yesterday morning, only to find it discharged to 10% by early afternoon. It hadn't been connected in that time. I charged it again in the afternoon, made sure it was running the latest software update, and it has discharged totally overnight again.
I see some others are suffering similar problems, has there been an update/fix yet?