The object never visibly changes position and it stops eventually with a different random y value after a different random length of time each session
untriedbonylangur.
It’s got an animator. Find out if that is moving it: disable or destroy the animator at runtime.
good idea, it turned out to be my billboard script that tied the sprite rotation to the camera. I just recently started using Cinamachine and the camera seems to constantly be making micro adjustments to the Y position ¯_(ツ)_/¯