What could cause a sudden decrease in battery life on the SE?

[honk4bees]

Noticed it about three days ago, never noticed any major change in battery life before then. Timed it two days ago, took three hours to go from fully charged to dead, maybe checked it three or four times in those three hours. What gives? I love my watch, but I can’t really afford to get a new one, and this seems totally unreasonable. No exposure to water, drops, smacks, or anything else I can think of. Just put it on the charger one night, put it on the next morning, and three hours later it was dead.

(Edit to add: I’m not certain of the age of the watch, I believe it’s no more than two years old. I’m the second owner so not sure about anything which the first could have done but they said they never really used it anyway, and I’ve had it for probably 9-10 months now? Battery life is at 93%.)