I don’t understand.

My cat that I just adopted a few days ago loves to hide under my bed. That parts fine. I know they like to hide. But my lack of understanding comes from why he will turn to run and hide when I walk near him. But only when I walk. Not when I’m down on his level. And when I block the entrance to under my bed he cuddles me and when I pet him, he licks me, purrs rubs against me and kneads. It’s like when I walk he is terrified of me