I checked your website and I see the issue.
In short
In your .htaccess file is the following code:
<FilesMatch ".(php4|php5|php3|php2|php|phtml)$">
SetHandler application/x-lsphp73
</FilesMatch>
This code is not compatible with our hosting and is causing the issues you’re having.
Simply removing it should make your website work normally.
I don’t see anything that suggests anything might be wrong on our end.
In detail
With this .htaccess code, you tell the server: “please execute my PHP code with the application/x-lsphp73 application”.
Looking at the name, I suspect that this application is LiteSpeed server with PHP 7.3. But we don’t use LiteSpeed server, and we don’t offer PHP version selection on free hosting (we currently run PHP 8.3 only).
This code is instructing the server to execute your PHP code using software that we don’t use, overriding our default PHP execution logic. The server doesn’t know what to do with this specific handler, so it doesn’t process it, and just sends the code to the browser. Since the browser also has no way to render PHP code, it will download it.
I’m guessing that you migrated this website from another hosting provider where this code did work. But our servers are clearly setup differently than theirs, so this code doesn’t work.