If there's an object obstructing or interfering with the wireless signal between the TV and the mobile device, the picture quality may be unstable or blurry when using one-touch mirroring or screen mirroring. To avoid this issue, remove any objects blocking the wireless signal between the mobile device and the TV. Placing the mobile device near the TV may also fix the issue.
In addition, the Xperia mobile device has a built-in Wi-Fi® antenna. If the built-in Wi-Fi antenna on your mobile device is covered, it may not attain the one-touch mirroring or screen mirroring features on your TV. Make sure that the built-in Wi-Fi antenna is not being covered by your hand to avoid unstable picture quality. Refer to the instruction manual of your Xperia mobile device for the location of the built-in Wi-Fi antenna.