Lots of small partial fills on my larger orders after hours. Why does this happen

I have a stock that I trade multiple times a week mostly on vibes. I make a lot of my buys after-hours in the 500-2000 range. These often fill over time at less than 100 shares at a pop. I often see partial fills at less than 10. I have no issue unloading during market hours. I've noticed this with a few other stocks I trade and am curious why this is. All are valued less than 10$ but not penny stocks

I originally bought it as a buy and hold but then noticed this after-hours activity and can make a couple of percent every week or 2 with no real effort. It's a very small portion of my portfolio but it's paying my bills. I use wealthsimple as my trading platform.

Edit: I am not naming the stock because I don't want to look like I'm trying to pump something. I am actually curious why this happens.