vscode.terminal.keybindings.jsonc

[
    // When no terminals are open, open a new terminal
    {
        "key": "ctrl+`",
        "command": "workbench.action.terminal.new",
        "when": "!terminalCount"
    },
    // When at least one terminal is open, focus on the terminal
    {
        "key": "ctrl+`",
        "command": "workbench.action.terminal.focus",
        "when": "terminalCount"
    },
    // When focus is currently on terminal, switch to the previous editor
    {
        "key": "ctrl+`",
        "command": "workbench.action.openPreviousRecentlyUsedEditor",
        "when": "terminalFocus"
    }
]