For how long did you own it? From what I understand, sometimes it runs out of charge sometimes it doesnt? If thats the case, then its normal. Especially if you’ve had it for a bit. Sometimes my watch would not even go lower than 70% when charged to 100%, sometimes I get back home and its at 30%.
Try AliExpress for loops. I’ve got a couple of straps and the Milanese loops as well, which I think go for the most amount of money. Very very cheap and good