I can't say I'm surprised, but it still sucks
This was mentioned in the
DL squeezing more revenue for less premium experience thread. But I'll still elaborate here.
Effective July 3, 2018 Delta customers connecting to their Delta Premium Select experience on transatlantic and transpacific flights will receive a Delta Comfort+® seat assignment on their connecting leg of domestic travel, pending availability.
This is part of the continued evolution of Delta’s onboard product that will offer more Delta Premium Select options with the delivery of more state-of-the-art A350 aircraft and the modification of the airline’s 777 fleet, in addition to creating a more seamless experience with our joint venture partners, Air France, KLM, Alitalia and Virgin Atlantic.
Source:
https://pro.delta.com/content/agency...and-trans.html