WashG1eaving foamy streaks after using for about 15 min. First time use

I recently bought washG1 and filled tank with only distilled water. After about 15 min, it started leaving streak marks from the right edge. I didn't fill any solution or soap in tank. Where is all that foam coming from ?! Does it gonna leave foam after every use? After clean, when I opened the dirt tray, it was also filled with foam.

When I did self cleaning, a lot of foam was coming out of the rollers from the right side. I had to put a rag to soak all that foam !