Abrupt Battery Drainage on Apple Watch 7

I have an Apple Watch Series 7, and the battery was working great. I've had it for three years, and it would last all day with no issues. However, one day last week, the battery drained within a couple of hours. It's been doing this ever since, not being able to hold a charge for more than 2-3 hours. Normally, a shrinking battery life is normal, but normally it's a gradual process, not an abrupt and acute one. Any ideas on if the battery somehow got damaged or if there's something I can do to fix it? Thanks!