Thanks for clarification!
One more question. In the past I can search for business award ticket (for example, 450K/business), as a surrogate for miles+copay upgrade.
For this specific flight AA61 DFW-NRT 3/15/2023, I can still purchase a 450K award business ticket. However this ticket is not shown as a C space in award search on EF. Do you know why is that? Where does miles award business ticket goes to?