Ctrl+P
The default is Ctrl+Shift+Left / Ctrl+Shift+Right; change it in settings.json:
Ctrl+Shift+Left
Ctrl+Shift+Right
settings.json
"terminalReorderingKeybinds.reorderPreviousKey": "ctrl+alt+left", "terminalReorderingKeybinds.reorderNextKey": "ctrl+alt+right"