I think something like that should work:
function my_acf_format_value( $value, $post_id, $field ) {
$value = round($value, 2);
echo $value;
}
// Apply to fields named "my_field_name".
add_filter('acf/format_value/name=my_field_name', 'my_acf_format_value', 10, 3);
The filter “acf/format_value” give the ability to modify the value of a specific field (here by field’s name).
https://www.advancedcustomfields.com/resources/acf-format_value/
Hope this helps 😉
