Hello,

Please synchronize the translation and try again. If it does not help, follow the steps to get the fix:

1. Please upload the file from this link: https://drive.google.com/file/d/17pRyCpJdReyl_wWyoTduwTUoQQqLkvGT/view?usp=sharing

2. Upload it into this folder deleting the previous one wp-content\themes\basel\languages\basel.pot

3. Find this file wp-content\themes\basel\inc\template-tags.php and replace the code shown on the screen: http://prntscr.com/o2s9ji

basel_header_block_search_extended()

switch ( $search_post_type ) {
	case 'product':
		$placeholder = esc_attr_x( 'Search for products', 'basel' );
		$description = esc_html__( 'Start typing to see products you are looking for.', 'basel' );
	break;

	case 'portfolio':
		$placeholder = esc_attr_x( 'Search for projects', 'basel' );
		$description = esc_html__( 'Start typing to see projects you are looking for.', 'basel' );
	break;

	default:
		$placeholder = esc_attr_x( 'Search for posts', 'basel' );
		$description = esc_html__( 'Start typing to see posts you are looking for.', 'basel' );
	break;
}

switch ( $search_post_type ) {
	case 'product':
		$placeholder = esc_attr_x( 'Search for products', 'placeholder', 'basel' );
		$description = esc_html__( 'Start typing to see products you are looking for.', 'basel' );
	break;

	case 'portfolio':
		$placeholder = esc_attr_x( 'Search for projects', 'placeholder', 'basel' );
		$description = esc_html__( 'Start typing to see projects you are looking for.', 'basel' );
	break;

	default:
		$placeholder = esc_attr_x( 'Search for posts', 'placeholder', 'basel' );
		$description = esc_html__( 'Start typing to see posts you are looking for.', 'basel' );
	break;
}

Synchronize the translations.

Best Regards