Entity annotations allows specify 'link templates'. In the future, a generator will use these link templates to create paths for router items. See #2350509: Implement auto-route generation for all core entities and convert all of the core entities.. Previously, a link template was used to reference a router item.
Route name patterns (e.g: entity.$entity_type.$relationship) are now consistent for all entity types. See the change log
Previous link template format
* links = {
* "canonical" = "entity.node.canonical",
* "edit-form" = "entity.node.edit_form",
* "delete-form" = "entity.node.delete_form",
* }
New link template format
After the change, the path is used.
* links = {
* "canonical" = "/node/{node}",
* "edit-form" = "/node/{node}/edit",
* "delete-form" = "/node/{node}/delete",
* }
RouteBuilderInterface::getCollectionDuringRebuild() got removed
With switching to paths, it was possible to remove RouteBuilderInterface::getCollectionDuringRebuild() again. It was added because there were cases that needed to get the entity routes while rebuilding the router. There are no known use cases for this anymore, so that method was removed.
If you used that method in your code, consider changing it, so you get the $collection passed along from your RoutingEvents::DYNAMIC event.
If this doesn't help, write some event subscriber which injects the collection into one of your services on that event.
