Dont’t be, it’s common use and had been for ages in writing. Especially in fiction writing.
[[em dashes have been around for centuries, wielded by writers from Emily Dickinson to Vladimir Nabokov to add rhythm, emphasis, and personality to their prose]]
They have been aroud for ever practically- even before the typewriter was invented- they fell out of use because there was no em dash key n the typewriters back when.
Just to add on to last post a bit. They can be used for instance to SHOW (instrad of tell about) a character always interrupting others, or show a person who is timid who always lets others speak over them ane cut them off. It can show someone who indecisive, unsure, etc.