Hydration Tracking Randomly Increases

I have noticed over the past few days I will either check my watch upon waking, or during the day I will go to add hydration and the watch shows that I've exceeded the goal by (normally) well over 2 litres. I have this issue when adding drinks on too, as just now I went to add 750ml to the hydration tracking and i tapped 330ml (my presets) and it went from 1800ml to 4300ml, ans i only tapped once. Is this an issue with the software or an issue with my watch?

It's a new watch, only a week-ish old. It also will vibrate during the day and tell me I hit my hydration goal too. Is this an ongoing issue with anyone else? My watch is fully up to date too.