MacBook Air: Battery Power getting drained while being charged.

I usually use my MacBook at 100% battery and plug it in on a daily basis but I do use the battery once in a while every week.

But this week, when I was having my class online, I saw the battery kept draining even though it was plugged in. So, I thought it was because of my high energy consuming online class software (Canvas) that my MacBook consumes the battery instead of power adaptor.

However, the next few days, I found that the battery still keeps draining even though I was just using Safari; no high battery consuming activities.

As you can see in the image attached, it shows that it is charing at the battery icon but actually it drained from 100% to 97% while charging and at the same time, in the battery information, it says NO for charging. I have done resetting the SMC setting to fix this but it doesn't help.

Can anyone tell me how to fix this issue, please?