The Mi TV 4A Pro comes in multiple sizes (32, 43, 55 inches). Firmware is size-specific . Installing the wrong update (e.g., 43-inch firmware on a 32-inch TV) can permanently brick your device.
Navigate to the Gear icon in the top-right corner of your home screen. mi tv 4a pro 32 inch software update download
Sometimes, OTA updates are rolled out in batches. This means the update might be available, but your specific TV hasn't received the notification yet. In this case, you can manually flash the update using a USB drive. The Mi TV 4A Pro comes in multiple sizes (32, 43, 55 inches)