The default keybindings in Symex mode treat increasingly nested code as being “lower,” and elements closer to the root as “higher.” This may be familiar from the sense of “tree” in computer science, which is “inverted” from the orientation of actual trees growing outside. You can, if you like, flip this to correspond to the latter, which was formerly the default orientation of Symex. The latter orientation would mean thinking as a squirrel would — going “up” to the nest and “down” to the root. Choose whatever you may find most natural by putting the following in the :custom section of your use-package declaration:
(symex-orientation 'squirrel) ; either 'squirrel or 'inverted (the default)