Charge significantly depletes, could this be a result ofovercharging?

I’ve had my watch for 18 months now (purchased on Amazon on July 4th 2020) and I believe my plug socket has weakened the battery. The plug socket says “5V - 2.4 A”. On one occasion I left the watch for a couple of hours after it had reached its maximum level (as I was out for most of the day) and after that, the battery life depletes very quickly. The type of battery this watch has is a 200 mAh lithium ion battery (manufacturer’s instructions do not mention the the exact length, width or thickness of the battery). What should I do to resolve this issue?