In the context of playing landscape games on a phone, the reason why the Google Fast Pair window doesn't prompt when pairing Xiaomi Buds 5 is the phone's operational design. During gameplay, phones often prioritize uninterrupted gaming experiences by suppressing notifications and pop-ups. Consequently, the Fast Pair window for devices will only appear once the game exits to the background.
To successfully pair the earbuds in such scenarios, it's advisable to either initiate the pairing process outside of gaming sessions or ensure the game is running in the background when attempting to pair. This approach helps maintain a smooth gaming experience.