This spider can fly??

OK. That's what happened: I was playing MC 19w07a in survival mode and I was walking in a desert. Then I found this spider floating up to the sky. I thought the spider can have a floating effect on it, but I looked up in Minecraft wiki and found it's not the reason. What's more, I changed into creative mode, flew up and punched it-- then it fell down for a few seconds, and floated up again!