Calling surface? Do you mean theme/wallpapers?
Clear phone app cache and restart device.
In op 7t or lower device the theme is different but now stock android
OnePlus decided to launch OnePlus 8T with Google Communication Suite as stock. That's why it is different than 7T, which uses OnePlus stock phone app.
Please use the search before creating a new thread, there is an existing thread already open for discussion
LOOP EP02 | OnePlus 8T Concept and the Watch!
by YRJ, 2021-01-05