commerce-8.x-2.8/modules/promotion/commerce_promotion.links.task.yml

entity.commerce_promotion.collection:
  route_name: entity.commerce_promotion.collection
  base_route: entity.commerce_promotion.collection
  title: List

entity.commerce_promotion.edit_form:
  route_name: entity.commerce_promotion.edit_form
  base_route: entity.commerce_promotion.edit_form
  title: Edit

entity.commerce_promotion_coupon.collection:
  route_name: entity.commerce_promotion_coupon.collection
  base_route: entity.commerce_promotion.edit_form
  title: Coupons