As an analogy, can you imagine being a startup that hired a developer, and months later finding out the bulk of the new Web app they "coded" for you was actually copy&pasted open source code, loosely obfuscated, which they were passing it off as something they developed, and to which the company had IP rights?
You'd immediately convene the cofounders and a lawyer, about how to make this have never happened.
First you realize that you need to hand the lawyer the evidence (against the employee), and otherwise remove all traces of that code and activity from the company.
Simultaneously, you need to get real developers started rushing to rewrite everything without obvious IP taint.
Then one of you will delicately ask whether firing and legal action against the employee is sufficient, or whether the employee needs to sleep with the fishes to keep them quiet.
The lawyer will say this kind of situation isn't within the scope of their practice, but here's the number of a person they refer to only as 'the specialist'.
Soon, not only are you losing the startup, and the LLC is being pierced to go after your personal assets, but you're also personally going to prison. Because you were also too cheap to pay the professional fee for 'the specialist', and you asked ChatGPT to make the employee have a freak industrial shredder accident.
All this because you tried to cheap out, and spend $20 or $200 on getting some kind of code to appear in your repo, while pretending you didn't know where it came from.