The answer surprised me.
I initially thought it should be a new panel to generate the title, but in fact
it is a ScriptTextEditor containing a CodeTextEditor, CodeTextEditor contains a text_editor, text_edit through set_draw_minimap (true) to generate minimap.
It stands to reason that text_edit created in the game can also generate minimap, but it seems that the interface is not exposed to gdscript
If you want to ask a question, you can say TextEdit's minimap
By the way, you can search minimap in godot editor and close or change it