Parsing MUI V5 DatePicker dateObject to date - material-ui

Question

I would like to validate my DatePicker field input from MUI V5 with Zod and React Hook Form.
<Controller
name = {id}
control = {control}
defaultValue = {defaultValue}
render = {({field: {ref,...field}}) => (
<LocalizationProvider dateAdapter = {AdapterDayjs}>
<DatePicker
label = {label}
value = {field.value}
onChange = {(id) => field.onChange(id)}
maxDate = {maxDate && maxDate}
minDate = {minDate && minDate}
renderInput = {(params) => (
<TextField
inputRef = {ref}
required = {required}
{ ...params}
fullWidth size = "small"
error = {!!errors[id]}
helperText = {errors[id]?.message?.toString()}
{ ...field}
/>
)}
/>
</LocalizationProvider>
)
/>
My sample validation schema
export const personalDataSchema = z.object({
birthDate: z
.date({
errorMap: (issue, _ctx) => {
switch (issue.code) {
case "invalid_type":
return { message: "Enter a valid birth date!" };
case "invalid_enum_value":
return { message: "Enter a valid birth date!" };
default:
return { message: "Enter a valid birth date!" };
}
},
})
.max(birthDateMin, "Employee must be older than 18 years!"),
});
The validation always fails because the value is an object, not a date.
How do I get the date picker field to return a date type?