This workflow will add product's vendor name as product tag. This task uses a prefix ("vendor-") i.e, the actual tag would look like vendor-Nike if vendor is Nike. You can change the prefix or remove it altogether by editing the workflow if you want. You can run this workflow manually on all products through the backdating tab to tag all products with their vendor names. Otherwise, this workflow will auto-trigger for specific products, whenever a product is created or updated.

Note: This workflow is configured to remove all tags starting with "vendor-" that will take care of removing older vendor tags if vendor has been changed and older vendor tag starts with "vendor-"