Wtf did I manage to do

This is (clearly 🤣) my first ever project. I got a frame look off Amazon and feel addicted already. Making this and trying different stitches was so much fun. What you’re seeing is the back of the work. Towards the top, beginning with the fuschia and moving up, I tried the twill stitch (1 under, 2 over, repeat) , two rows of soumak stitch and then back to twill. Finally, I attempted to do a hemstitch (and ran out of yarn near the last few warps). Looking at the back, it appears I somehow completely missed every 3rd warp. I have no idea how I did this. Is this normal for a twill stitch?