system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How people discover complicated bugs in video games that take a lot of specific steps to reproduce.

I like watching speed runs and when watching the Zelda OOT speedruns, they often take advantage of a lot of different glitches. Those glitches often required a bunch of steps and all of which have to be done in order, in very specific ways.

I also remember learning a duplication bug in PSO (Gamecube) when I was younger. You had to do a lot of crazy steps to get it to work. It always worked when you did it right, but it was pretty difficult because of how exact you had to be.

So how do people figure out these types of bugs?
gpt
Another way is to pore through the code of a game. You'll sometimes find minor inconsistencies in the code that you can exploit. 

DayZ used to have a duplicating glitch that was discovered from the code. Somebody looked at it and realized that your inventory only saves when it is closed. So, they tried having somebody empty your inventory, then you close out of the game without ever closing your inventory. Next time you load in, your inventory reverts to the last save, which makes it full again. Now you and your friend have each have a copy of all the shit that was in there.