At least according to an atheist Jewish ex of mine, it’s fine to use “Jewish” to refer to the ethnicity too. She would just specifically “ethnically Jewish” or “religiously Jewish” or whatever else if it wasn’t clear from context - neither being more or less Jewish than the other.
“Jewish” is an ethnicity as well as a religion so one can be ‘of Jewish descent’ without practicing Judaism.
I think that’s the short answer.
Please correct me if I got any terminology muddled up.
At least according to an atheist Jewish ex of mine, it’s fine to use “Jewish” to refer to the ethnicity too. She would just specifically “ethnically Jewish” or “religiously Jewish” or whatever else if it wasn’t clear from context - neither being more or less Jewish than the other.