Chabad is not Ashkanazi. The siddur and minhagim differ noticeably enough.
I think you might be confusing davening Nusach Ashkenaz with being ethnically Ashkenazi.
Most members of Chabad *are* Ashkenazim, even if they don’t daven Nusach Ashkenaz. Likewise, many Ashkenazim daven Nusach Sefard despite not being Sefardim.
The Wolf