Please help! Battery stops charging at lower and lower percentages (UX330U Zenbook)

Hi - this problem began a month ago. My laptop would be fully plugged in and charging/resting, but the battery would say it's only at 84%. Every day, the max percentage would go down. Now, it's perpetually plugged in and perpetually at 12%, and I'm beginning to really feel the lag/slowness in loading, scrolling, sending messages, etc.
I've troubleshooted tech problems on my own in the past, generally by relying on Google, but this is the first time that I literally could not find any other info whatsoever about my predicament. I'm a student taking classes online and I need my laptop pretty much all of my waking hours, so you can imagine how worried I am for when that percentage inevitably gets to 0%.
I've had this laptop for almost three years, and one thing of note that I can think of is that a year ago, I spilled ramen soup on some of the keys (and some might have gotten into that vent-looking area between where the laptop folds). But at the time I immediately turned my laptop off and did my best to clean/dry everything, and it's been alright since.
Do you think soup is the culprit? Are my laptop batteries dying somehow? I'm worried this isn't a glitch or bug I can easily fix, and I might actually have to get it sent in to be fixed - this would be terrible news as in these quarantined times I literally can't survive a day without my laptop (I need it for both school and work, every day).
Any help would be greatly greatly appreciated!
Edit: I just downloaded something called BatteryInfoView. As you can see, the current full capacity is "listed" as being 31.7% of the original (already very low), but the current capacity value only charges up till 11.6% maximum (this is after leaving my laptop sitting there for an hour with no major applications running). Why is the capacity falling so fast??
Comments
Hello Vicky,
Please kindly send your device to service center.
Thank you.
But do you know why the battery life is draining so suddenly? This only started within the span of a month. And with my past laptops, they would still charge to 100%.
Hello Vicky,
There might be different reason.
It's quite difficult to tell you the exact reason from word description.
Thank you.
But what do you suspect could be the reason? Can you list a couple of the most likely causes, just so I can research the topics a bit more before a make a decision to take my laptop in to get fixed? Please understand it would be a huge inconvenience for me to part with my laptop for 2+ weeks, as both my school and work is done through it, not to mention the monetary costs.
i suspect battery current charging capacity too low, so i would recommend you to change old battery to new battery from asus service center.
Also i might have suspect the power settings in windows os, change the power plan to balanced and enable battery saver
But normally when battery charging capacity is low, does the battery not still charge to 100%? (Just the 100% is less effective?)
The power plan is on balanced already and battery saver is also on.
your laptop battery designed capacity has totally reduced to 18064 from 57057 .
now if battery charges to 100% means it completes to 18064 , not 57057.
100% = 18064
50% = 9032
25% = 4516
10% = 1806.4
5% = 903.2
so i recommend you change the battery soon , say within end of this month