Sometimes the server config return bytes (instead of MB), this little helper fixes the display in the site health plugin.

repair-bytes.php

<?php

/**
 * Returns always bytes for every config (M, K or G)
 *
 * @param  [string] $size_str Input from config.
 * @return [int]           Return in bytes.
 */
function return_bytes( $size_str ) {
	switch ( substr( $size_str, -1 ) ) {
		case 'M':
		case 'm':
			return (int) $size_str * 1048576;
		case 'K':
		case 'k':
			return (int) $size_str * 1024;
		case 'G':
		case 'g':
			return (int) $size_str * 1073741824;
		default:
			return $size_str;
	}
}

/**
 * Returns bytes in formatted way
 *
 * @param  [int]   $bytes        Amount of bytes.
 * @param  integer $precision    Number of digits after the decimal point.
 * @return [string]              Formatted string with unit.
 */
function format_bytes( $bytes, $precision = 2 ) {
	$units = array( 'B', 'KB', 'MB', 'GB', 'TB' );

	$bytes = max( $bytes, 0 );
	$pow   = floor( ( $bytes ? log( $bytes ) : 0 ) / log( 1024 ) );
	$pow   = min( $pow, count( $units ) - 1 );

	// Uncomment one of the following alternatives.
	$bytes /= pow( 1024, $pow );
	// $bytes /= (1 << (10 * $pow));

	return round( $bytes, $precision ) . ' ' . $units[ $pow ];
}

/**
 * Repairs the display of the memory_limit debug info
 *
 * @param  [string] $info Bytes with unit from config.
 * @return [string]       Formatted bytes with unit.
 */
function repair_bytes( $info ) {
	$memory_limit      = $info['wp-server']['fields']['memory_limit']['value'];
	// Renamed from upload_max_size to upload_max_filesize in https://core.trac.wordpress.org/changeset/48801
	$upload_max_size   = $info['wp-server']['fields']['upload_max_filesize']['value'];
	$php_post_max_size = $info['wp-server']['fields']['php_post_max_size']['value'];

	if ( '-1' === $memory_limit ) {
		$memory_limit .= ' (no limit)';
	} else {
		$memory_limit = format_bytes( return_bytes( $memory_limit ) );
	}

	$upload_max_size   = format_bytes( return_bytes( $upload_max_size ) );
	$php_post_max_size = format_bytes( return_bytes( $php_post_max_size ) );

	$info['wp-server']['fields']['memory_limit']['value']        = $memory_limit;
	// Renamed from upload_max_size to upload_max_filesize in https://core.trac.wordpress.org/changeset/48801
	$info['wp-server']['fields']['upload_max_filesize']['value'] = $upload_max_size; 
	$info['wp-server']['fields']['php_post_max_size']['value']   = $php_post_max_size;
	return $info;
}
add_filter( 'debug_information', 'repair_bytes' );