Microsoft breaking consumer rights to product (Forza Horizon 4 and 5)

That is the problem. Microsoft noticed the price error almost on the same day (by changing the price back on the same day). However, it took them 5 more days to start to inform anyone who made the purchase. Why is this long delay? Sending an automatic email to anyone purchased at this price should be a simple task. It just feels like luring the customer to play it for 6 days, so they have to re-purchase the game if they want to continue with it. Yes, you can play it on Game Pass, but not the hot wheel DLC.

Microsoft has the right per TOS to revoke pricing errors

https://www.microsoft.com/en-us/storedocs/terms-of-sale

Microsoft reserves the right to refuse, reject, cancel, terminate or not to process any order (including accepted orders) at any time, refunding you any monies you have paid for the order, for reasons which include, but are not limited to, if you have not met the conditions specified at the time of the order, if your payment cannot be processed, if the ordered Products are not available, where the price or other material information on the Store is inaccurate or for other errors. In the event of pricing or other errors, we may, in our discretion, either (a) cancel your order or purchase or (b) contact you for instructions. In the event of cancellation, your access to any associated Digital Content will be disabled. ”

It was a bug as that was never supposed to be that price.

it was not a bug since those prices are manually set for each country as far as i know

Any progress you have made is still there. You can re-purchase the game or play it on Game Pass And pick up right where you left off

Not honoring egregious misprices is standard across retail in general. When I used to be a buyer for a major chain, we would offer misprices at our cost. That is not something you can do here.