Luckily, there is a workaround for that as well. However, this has an effect on any Labels that you might use in Gmail.
To break yourself out of this additional subfolder and have all these folders listed directly under your mailbox in Outlook, you can set a root folder for your Gmail IMAP account.
When you are using a Gmail account over IMAP in Outlook, you’ll also automatically get an or folder containing all the “system folders” of Gmail itself.
