In spite of the name I think the overwhelming majority of the tasks were things that could be done by LLMs and they're probably getting flooded by people using bots to do exactly that. Even before the age of LLMs Mechanical Turk data was pretty bad because you'd have a bunch of people racing to answer questions as quickly as possible to get their $0.25 or whatever. So it was essentially a test of 'can you input random answers as quickly as possible while paying enough attention to notice the attention question that says to mark d.'

Any remotely open platform for this sort of stuff is going to wrecked by LLMs. But making some sort of high trust, high verification market is going to end up sending prices high enough that it becomes an unattractive proposition for use. And even in that case it's just going to be a cat and mouse game of people figuring out how to game the system enough to get trusted before handing it off to the LLM.