It's not limited to just filing lawsuits. There are federal agencies you can file complaints with that will then tip off investigations and you can do that for free.

These types of firings, where the employee was given no negative feedback, there is no paper trail, evidence, etc. creates the type of gray areas that can easily lead to findings in favor of the employee if she were to file something for say sex discrimination. Cloudflare may have to go and find other instances where they fired non-protected class employees in a similar fashion. At the very least, it's going to be a PITA for their HR/legal team and may cost them some fines as well.