Rename a file based on date in file

I have searched the forum as sure someone has already asked this.
I want to rename a file of the format
5086583_BR-308212101001_INV_BR-308212101001-20190725_20190725
I can use 5086583_BR-308212101001_INV_BR-308212101001- as supplier ID and use that but not sure how to use last 8 digits of the file name that denotes the invoice date.
Want to end up with Supplier Bill Invoice Date with date formatted as 2019_07_25.
Thanks
Michael
I want to rename a file of the format
5086583_BR-308212101001_INV_BR-308212101001-20190725_20190725
I can use 5086583_BR-308212101001_INV_BR-308212101001- as supplier ID and use that but not sure how to use last 8 digits of the file name that denotes the invoice date.
Want to end up with Supplier Bill Invoice Date with date formatted as 2019_07_25.
Thanks
Michael