Since the last update (version 10 (22909) php code is no longer or not correctly executed. I have tested on the local server (XAmpp) independently of RW-elements with <?php phpinfo(); ?> that php runs. If I add a customer html and insert the code
<?php echo ‘<b class='text-green-500‘>Hallo World_1</b>’; ?> <p><b class=‘text-green-500’>Hallo World_2</b></p> <p>I get the following result</p> <p>Hello World_1’; ?><br> Hello World_2 (green and bold)</p> <p>The file is index.php<br> The ‘<p>’ and ‘</p>’ are not part of my code, but were probably added when I created the post</p> <p>Before I confuse you all. This is the code and the other is the result<br> <img src="https://europe1.discourse-cdn.com/flex005/uploads/realmacsoftware1/original/3X/b/6/b6ad124cd275b147a7f5ff77482b3b772b5b87a2.jpeg" alt="Bildschirmfoto 2024-09-27 um 16.11.32" data-base62-sha1="q41HCvRaJUgk2f53qkVXql44mnU" width="690" height="467"><br> <img src="https://europe1.discourse-cdn.com/flex005/uploads/realmacsoftware1/original/3X/1/e/1efe19264629d675cd5842b606077e678d9eb10f.jpeg" alt="Bildschirmfoto 2024-09-27 um 16.15.30" data-base62-sha1="4qaJ4U73nv2mePbt1OsPfoVDc9p" width="345" height="123"></p>It’s a bit difficult to read your code because you haven’t included it in a preformatted text block. 
I have just tried this code and it works perfectly in Preview.:
<?php echo "<b class='text-green-500’>Hallo World_1</b>"; ?>
Looking at your code, you are using a single quote that looks a bit odd (inclined). I suggest you stick to double-quotes and single quotes and see if that works.
Hope this helps? 