Imo, this is most likely AI. Facebook and Instagram both have incredibly sophisticated spam preventative measures. These companies are likely using artificial intelligence to generate brand new and highly intelligent scripts that continuously change to evade spam detection tools. Same thing happened on Twitter (You can look at my post history for an example). There was a bot spamming on Twitter and it had run out of credits for GPT resulting in the AI instructions to start being spit out instead of the fake messages it was supposed to produce.