PHP - 服务器输出垃圾 - 可能是编码问题

Since yesterday, my server is adding some garbage characters to any script in PHP. If I look at my code with view source, I see some spaces and if I display a JSON string, it is considered invalid.

If I take this simple example:

<?PHP
echo "hello";
?>

It displays hello but in the source code I see a blank line before hello. The encoding of the file is in UTF8 without BOM (did it with Notepad++)

If I use file_get_contents to load the PHP file and then use rawurlencode before outputting the content, I get the following garbage before hello:

%EF%BB%BF%EF%BB%BF%EF%BB%BF

My first thought was that it was an encoding issue but I checked the concerned PHP file(s) and they are all in UTF8 without BOM. The only solution I have found is to remove this string of garbage each time before treating the content of a file.

I'm using Wordpress and the problem suddenly appeared yesterday while I had not modified any file.

Do you have any idea?

Thanks

Laurent