Slashes before Double Quote marks

Short answer: those backslashes are almost always added before the data reaches the page — either by an automatic, server-side escaping step (the old “magic quotes” behaviour) or by application code that escaped the value before storing or re-outputting it. @demo pointed to the magic-quotes era; that feature caused exactly this symptom and was later deprecated/removed because it led to double-escaping and other problems. (wiki.php.net)

How to diagnose: inspect the page source — if the backslashes appear in View Source they were emitted by the server; if they only show in rendered text but not in source, client-side code is likely altering the string. For a reliable server-side check, write a short debug dump of the incoming data (for example, serialize/var_export the POST array into a temporary file) or inspect the raw input stream; use that short-lived dump to see whether the slashes are present before any formatting. (Use a temporary path and remove the file afterwards.) (php.net)

How to fix it properly: stop relying on global escaping and treat escaping as a context-specific output step. Store the original text (no global addslashes), protect database writes with parameterized/prepared statements, and escape only where needed for HTML output (so quotes display cleanly and XSS is prevented). For HTML output, use the standard HTML-escaping routine so user quotes are shown correctly while keeping the page safe. (php.net)

To let visitors save a generated page, don’t ask them to “Save As” from a form POST. Instead either (a) save a server-side static HTML file and link to it, or (b) stream the generated HTML back with an HTTP Content-Disposition: attachment header so the browser prompts to download a .html file. Below are two lightweight patterns to implement those options.

<?php
// stream-as-download pattern
header('Content-Type: text/html; charset=UTF-8');
header('Content-Disposition: attachment; filename="profile.html"');
echo $generatedHtml;
exit;
?>

<?php
// save-to-disk pattern
$path = '/path/to/saves/' . uniqid('profile_', true) . '.html';
file_put_contents($path, $generatedHtml, LOCK_EX);
echo '/saves/' . basename($path);
?>

Content-disposition behaviour is standardized (browsers will usually prompt/save when you use attachment), and server-side file writes follow the usual PHP file APIs. (datatracker.ietf.org)

Notes: @GaryKing’s and @Antonbomb22’s suggestions are useful quick workarounds for display, but the long-term fix is to remove/adapt any automatic-escaping in the request flow and adopt context-aware escaping (HTML on output, parameterized SQL on DB writes).