VuetifyJS: how to get rid of the v-stepper component elevation?

Not elevation-{0}, but elevation-0.
Elevation docs:

You can set an element's elevation by using the class elevation-{n}, where n is a integer between 0-24 corresponding to the desired elevation.

So actually you need to remove parentheses as well.
Should be clear because you can't use parentheses in class names as far as I know.

just put the following

<v-stepper v-model="e1" class="elevation-0">