The bitrix:sale.order.ajax component in the user block is substituted with an extra 7 in the phone number when changing the payment method. How to fix?

Question

1C-Bitrix

We fill in all the blocks in the form:
Delivery
method Payment method
User (full name, phone, email)
Then, we change the payment method, and the User form is updated and an extra 7 is inserted in the phone number field at the very beginning, and the phone number moves to the right. This seven eats up the last digit, replacing it with itself at the very beginning.
For example, it was like this:
[phone]
after changing the form of payment is already like this:
[phone]

Answer 1

Somehow I came across such a topic, the problem was in the phone input mask.

Answer 2

why an extra 7 is substituted in the 1s Bitrix phone number