It’s a base64 encoding. I did a similar thing in changing the code directly in the database. Most editors (I use emacs) can do the base64 encode/decode. After many frustrations, I am standing up an alternate solution with a different PHP approach that allows you to put code directly in the page via the editor with inline tags. If you have a lot of code to embed, I found a sample that shows how to do a short “include” that can bring in a large file at runtime.
https://www.ads-software.com/plugins/insert-php/
