If the disconnected device is indeed suspicious, to keep your information safe, you should change your { -product-firefox-account } password in your account settings. You should also change any other passwords you saved in { -brand-firefox } by typing about:logins into the address bar.
若断开连接的设备确实可疑，为了确保您的信息安全，应及时到“账户设置”中更改 { -product-firefox-account }密码，并在地址栏输入 about:logins，更改保存在 { -brand-firefox } 的所有网站密码。