I’m getting the error too, and unfortunately, modifying the core plugin is the only fix.
This worked for me:
// disable acf css on front-end acf forms
add_action( 'wp_print_styles', 'my_deregister_styles', 100 );
function my_deregister_styles() {
wp_deregister_style( 'acf' );
wp_deregister_style( 'acf-field-group' );
wp_deregister_style( 'acf-global' );
wp_deregister_style( 'acf-input' );
wp_deregister_style( 'acf-datepicker' );
}