The moss balls did this when I had them in their original tank which was 5.5 gallons and went back to green a few weeks afterwards. They have grown a bit since I first got them 8 months ago. I did squeeze them a bit and rolled them around a bit.
they’ll got back to being green soon. I am currently looking at imported bettas and picked one I will get. It’ll take about 2 weeks to get him, but that’s fine.