Hi
@Christina @Yaros,
I've also encountered this issue about the phone number field for those using 2checkout payment gateway and just figured out recently and lose a lot of potential sales because of this.
I am using Davinci theme. Currently, the plugin/theme only highlights the field in red when it is left blank. It would be a big help and greatly appreciated if you can also add below notification on the phone number field "Enter a valid phone number". This can also be added on the other customer information fields as well to ensure that customers are being notified properly when they accidentally left the fields blank instead of just only highlighting it in red.
NOTE: Below screenshot was taken from another platform and is just for reference only.