I'm sorry this is happening. AI is so puroposefully unregulated and a capitalist hellscape. It's good there is some justice but stinks that they were able to get away with stealing from you,
my work has been scrapped before, which i will never be happy about and not sure i can do anything about, but yours is copywritted about should be better protected.
i had no idea that one had to register their writing with the LOC either.