[Vuejs]-Vee-validate: Custom rule gets multiple times called

I believe it may be this.

You need use blur behavior. There are alternative events that might give you the same behavior of blur using data-vv-validate-on attribute to override the default events.

Examples:

For the multiselect it emits close event when the dropdown is closed which is also when the user leaves the control.

<multiselect data-vv-validate-on="input|close" ...>

For the date-picker you can instead validate on closed since that event emits when the user leaves the control.

<datepicker data-vv-validate-on="input|closed" ...>

VeeValidate Doc

I hope this help.