Hello
If there is issue with cart update so that means that default theme js is overwrite by other js .
If you remove the app but still ,By default app created file(snippets as well) is not deleted.
Firstly take a backup of the theme and then follow this steps:
You need to go the "Edit Code" and go to "theme .liquid" and check is any snippet or js file is included (generally app name based file are created) and remove it.
I hope that process helps you .
Thank you
VITIX DEV
