woocommerce/plugins/woocommerce-admin/client/navigation/components/favorite-button/style.scss

.woocommerce-navigation-favorite-button.components-button {
	.dashicon {
		margin: 0;
	}

	.dashicons-star-empty {
		color: $gray-600;
	}

	.dashicons-star-filled {
		color: $alert-yellow;
	}
}