Can you break this down a bit more? I've heard about making markets in relation to FTX but didn't really get the full picture.

You can Google it or ask an LLM. It's not magic. This is common knowledge.

Okay. That's largely independent of the maximum damage caused by a bug.

No.

In this case KCG was doing the opposite of making markets --- they were taking --- they were eating the spread over and over and over again until they ran out of money.