Why doesn't the mask work on computed property?

Question

Vue.js

The v-mask plugin is installed.
It is written on input(v-model='phone', v-mask='+7 (###) ###-##-##')
When I enter a number, everything is OK and it turns into +7 ( 999) 999-99-99
Then I need to send the number to the server in the format 79999999999
I get the same number from the server 79999999999 I
cut it with replace + split
And everything is inserted into the same input through the computed property when it arrives from the server, but it is displayed in this input without using a mask, that is, 79999999999
Maybe someone came across?