Purchase Order displayed status different with doc.status


I found an Issue in Purchase Order status, when “per_billed” is 99.999909 and “per_received” is 100.

The document label in UI informed that the Document already “Completed”, but it show in filter status “To Bill”, and when I check on cur_frm.doc.status it shows “To Bill”

this is my frappe and erpnext version:

I guess there is different condition for label Completed and doc.status To Bill, and I don’t know where string “Completed” come from ? because I check on cur_frm.doc cannot find string “Completed”

Anyone know regarding this issue ? and how to fix it ?
Thank you