Sir, this is not how the internet works.

Indeed it’s not. That’s why your claim that you can use Photopea without using their resources is BS.

Photopea does not use the developers’ server to do these tasks

Well, it uses the servers to do something and you refuse any compensation.

If I disassembled the obfuscated code and replaced those online references, I’m pretty sure the whole thing would just work.

Then do and host your own version.