Hi! My name is Aj and Im an Independent Advisor here to help! I am sorry to hear about your saved game progress. Kindly try these..
Make sure the signed in account is the account the you use when you save your game progress.
Restart the game and wait for a few minutes for cloud save to download.
If above wont work then you have to contact Xbox support directly at support.xbox.com/contact-us. Sign-in using the account linked to Xbox/Steam game then choose the category related to your issue, for example Games & Apps > Forza Horizon 5 > Cloud saves or account. From here you can now choose from virtual agent (automated help), request a call back from an Xbox support agent or live chat with support.