In almost all cases, TikTok's offering would be considered a derived work because you cannot swap out the OBS part for another and still have it work. So they are likely in full violation unless they agree to open source all their code. Seems like a pretty open and shut case to be honest - that is, if they intend to pursue legal action and the powers that be rule appropriately.
- pay damage for the violation the the client, given that's only beta that would likely not amount to much
- and stop the beta program, while replacing their OBS dependency with something completely different.