Battery reduces by 1%, never goes up again and then freezes computer?

It’s really weird, whenever I search for this particular issue I never see results, but for about a month now, every 3 days the maximum battery life would reduce by 1%, then never go past it again. I always keep the laptop plugged in. Is this dangerous for the laptop’s battery? I have moderate to high computer usage on fairly low-end applications, so this issue shouldn’t be happening. I got this laptop about 7 months ago.

Edit: I don’t really have any details for it other than it consistently does it every 2-3 days, and my current maximum is 89% capacity. Freezes occur and last for like 1-2 minutes, it’s become a nuisance.