Get ACF custom field value for the current logged in WordPress user

functions.php

/**
 * Shortcode to get ACF field value for the current user.
 *
 * This shortcode retrieves the value of an Advanced Custom Fields (ACF) field
 * for the currently logged-in user.
 *
 * Usage:
 * [acf_custom_field field_name="your_acf_field_name"]
 *
 * The field_name attribute corresponds to the ACF field name.
 * For more details, see the ACF documentation:
 * https://www.advancedcustomfields.com/resources/field-settings/
 *
 * @param array $atts Shortcode attributes.
 * @return string ACF field value.
 */
function acf_custom_field_get_shortcode( $atts ) {
	// Extract the attributes passed to the shortcode
	$atts = shortcode_atts(
		array(
			'field_name' => '',
		),
		$atts,
		'acf_custom_field'
	);

	// Get the current user ID
	if ( isset( $_GET['user'] ) ) {
		$current_user_id = sanitize_text_field( $_GET['user'] );
	} else {
		$current_user_id = intval( get_current_user_id() );
	}

	// Ensure the field_name attribute is safe
	$field_name = sanitize_text_field( $atts['field_name'] );
	if ( empty( $field_name ) || ! $current_user_id ) {
		return ''; // Return empty string if the field name is not provided or user not logged in
	}

	// Return the ACF field value for the current user
	return do_shortcode( '[acf field="' . esc_attr( $field_name ) . '" post_id="user_' . esc_attr( $current_user_id ) . '"]' );
}

// Register the shortcode
add_shortcode( 'acf_custom_field', 'acf_custom_field_get_shortcode' );

Add this code in your child theme's functions.php file and use this shortcode anywhere on your site to get the custom field value for your current logged in user as,
[acf_custom_field field_name="{your_acf_field_name}"]

The ACF field name comes from the ACF field setting for the field that you have created with ACF.
https://www.advancedcustomfields.com/resources/field-settings/