Kenmore side by side water freezing in bottom

Hi - I have a sie by side Kenmore about 8 years old. I have noticed that in the very bottom of the freezer side I have a slow but steady stream of water coming in from the back and freezing. It’s not a lot but about every month I have to pull the bin above it out and get rid of the frozen block. No water on the outside. After looking I noticed a plastic tube behind the grill and can see the stream starting at that point. Any suggestions on what I should look for as for the source of the water. It’s odd because its the freezer side and I wouldnt expect to see water coming in on that side. Its a front free freezer so I was thinking maybe the defrosting cycle may be involved.