Presumably megacorp's laywers are engaged with you doing due diligence before the acquisition, will be looking into this, and evaluating the license. Maybe they have prior licensing agreements with Meta, or plan to replace your use of Llama with something different, who knows.
OTOH if you are being acquired by Elon Musk, then there may be no due diligence, he will tear up any existing license agreements, spend the next year bickering with Meta on Twitter, then be sued to comply.