I've attached a video to see the issue clearly.
I fixed this by restarting the unity project.
To replicate, during editing a file's animation, select a random object outside the character GO (such as an axe) while pose mode is on, child it to the GO you're animating in clip editor, I tried to align the axe to the arms of my character (was still learning how to child-of constraint), then viola. I messed up unity's editor.
Customer support service by UserEcho