We had a Rest Export view on one site outputting JSON data which was getting imported into another site via a migration. After upgrading from Drupal Core 10.2.8 to 10.3.6 the import stopped working. What we found was that the JSON data being exported used to have a root key of "data" all the objects were wrapped in, and this key disappeared after the upgrade. We've updated the migration to fix the issue, but I haven't been able to pinpoint a change in Drupal Core which would have done this.
This is not urgent/important but if anyone had any insight that'd be wonderful.
Active
10.3 ✨
rest.module
For what it's worth, in separate, fresh 10.2.8 and 10.3.6 sites, I created REST export view displays for the Content view. In each version there is not a root data key.
Oh that's interesting. I'm going to attribute this to PIBKAC / user error then. Thanks!