Eli5: How are leaks from video games found inside the game’s files before it’s even released?

Question

Eli5: How are leaks from video games found inside the game’s files before it’s even released?

In: 1

Answer 1

It’s just code, that’s readable but not accessible while playing the game.
Ex. In Skyrim, with console command you can go to that room that has a chest with everything. Now image playing on XBOX, that room is still there just impossible to access.
Testers “read” the code to see what’s there but not accessible in game.