I went in to the theme code to troubleshoot it and actually found out it is a part of theme contact form styles which is performed by the following codes.

if( isset($atts['style']) && $atts['style'] == 'style2' ) : ?>
				#contact-form-<!--?php echo esc_attr( $atts['id'] ); ?--> label {
					display: none;
				}


#contact-form-<!--?php echo esc_attr( $atts['id'] ); ?-->.contact-form input,
				#contact-form-<!--?php echo esc_attr( $atts['id'] ); ?-->.contact-form textarea {
					text-align: left;
					border-radius: 25px;
					padding: 29px 30px;
					border-width: 0px;
				}