What is the current way of defining the ref for an innerRef attribute using TypeScript?

When using typed input:

const myRef = React.useRef<FormikProps<YourFormValueType>>(null);

return <Formik<YourFormValueType>
innerRef={myRef}
{...formikProps}
        />

Since TypeScript is not really helpful i used as casting.

<Formik innerRef={instance=>{formikRef=instance}} {…otherProps}/>`

This however makes a non-constant formikRef variable

let formikRef = useRef(null) as any;

I do not think this is correct way with 2.x