function _remove_theme_attribute_in_block_template_content( $template_content ) {
	$has_updated_content = false;
	$new_content         = '';
	$template_blocks     = parse_blocks( $template_content );

	$blocks = _flatten_blocks( $template_blocks );
	foreach ( $blocks as $key => $block ) {
		if ( 'core/template-part' === $block['blockName'] && isset( $block['attrs']['theme'] ) ) {
			unset( $blocks[ $key ]['attrs']['theme'] );
			$has_updated_content = true;
		}
	}

	if ( ! $has_updated_content ) {
		return $template_content;
	}

	foreach ( $template_blocks as $block ) {
		$new_content .= serialize_block( $block );
	}

	return $new_content;
}