It's not actually that surprising... hair may "look" one way and physically be another story completely. Sulfates/silicones are incredibly drying to the hair.. you need the sulfates to strip the silicones off, the silicones "hide" the drying damage done by the sulfates, etc... that's the bad cycle we break using the CG method. I think sometimes dry hair can also seem lighter and bouncier which are things we often associate with being in "better" shape but it's not always the truth.
When you first go CG and stop that cycle your hair can look worse for a while. Your hair is damaged and nothing is "hiding" it now. Your hair will eventually recover, but I think a lot of that process has to do with figuring out what works well for your hair and how to bring out the qualities you appreciated before, but in a healthier manner.
I found that personally I need a LOT more moisture in my hair than I ever thought possible. I also need way more gel than I thought was realistic. I've also found some products that just don't agree with my hair - leaving it flat, heavy, and often with a gummy/sticky feeling. When I get it right, I have soft, bouncy, and shiny curls.