It doesn’t matter if someone provided the fertilized egg. Woman A has a child and then it becomes part of Family B, sometimes with money changing hands and/or the threat of lawsuits or jail if Woman A has a change of heart.
The only way this can possibly be morally acceptable is in very carefully vetted on-off situations AND no penalty or pressure for a changed mind.
There is no morally-defensible way to do this “at scale”. Please do more research if you have even the slightest doubt.
But... why? Most women I know are fine and even happy with the pregnancy part. Why would they want to outsource that part? They love the attention. The birth part? Not so much, but that part is difficult to outsource.
I’ve witnessed 7 births in person (cesarean, vaginal natural, and vaginal with epidural). Though I haven’t experienced it myself, I’m fairly familiar with childbirth.