Using /setblock to place a structure block defaults to save mode, unlike placing one by hand

The bug

Using the /setblock command to place a structure block, it sets the default mode to Save. This is inconsistent with the default mode when placing a structure block by hand, which is Load.

How to reproduce

1. Give yourself a structure block by running the command /give @s structure_block
2. Place it down and open its UI
   Notice how the default mode is Load
3. Run the command /setblock ~ ~ ~ structure_block
4. Open its UI
   Notice how the default mode is Save