I tried the “If Menu” plugin and one other that does the same thing — add fields to the menu item editing form to control visibility. These plugins work okay when using a default theme like 2019. However, when I use Graphene, their UI appears on the screen twice:
I debated whether to report this to you or to the plugin makers, but since two similar plugins fail in the same way, I think this is more likely your problem.
I reproduced this in a brand new installation with no other plugins besides that one.