What's to investigate?

You even put the code in your git for doing exactly what you did.
Redirect miners to another pool.

Here:
https://github.com/ctubio/php-proxy-stratum

One block found by one miner to your solo - you sent the work to FUPool and he found an FUPool block so got nothing from you
then after that happened you continued to send solo work to FUPool but changed it to a new username.