It lags a lot when I write on my ipad

Around a week and a half ago, I started noticing that there are much delay when writing on note apps on my Ipad. I've tested on Goodnotes and Notes and they seem to lag equally. When I'm dragging the stylus across the screen, it felt as if I was 'drizzling' the line instead of it appearing immediately like a real-life pen. Because of the slow response time, the curves that I draw becomes more angular, which makes it a lot harder to write since I have to deliberately slow myself down a lot in order to be legible.

It couldn't have been my apple pencil since I had just bought a new one two weeks ago and when tested with my friend's Ipad the pencil shows no issue.

I don't know if it's the new 16.2 updates that caused this since even though it was released last December, I had postponed the update for a really long time and perhaps it updated on it's own when I turned it off and charged it. All I know is that I saw a significant UI change a few days around the lag.

I've actually taken my Ipad to iService. However, the staff told me that there's nothing I can do much but to factory reset the system. I don't really want to reset it since there's a huge amount of documents that I have stored in it, and my icloud is already full.

What exactly do you guys think is happening to my iPad and possibly the apple pencil? What could I do to fix it? Factory reset will be my last resort.