It's a good question.
I do think social media have research groups that can develop such tools, and they could have this warning. I think it's okay to show messages and warn people to pay attention.
It could be flagged with a certain degree of confidence, and maybe another thing they could add is whether people agree or not: “Thumbs-up or thumbs-down. Do you agree with this?” Maybe having people's opinions: “This seems like fake or disinformation.” People agree or not. Maybe have users label that. Some of them might not be saying the truth, but still the number of users who vote that this is correct or not....
There are ways. It is difficult, but there are ways. I think they could do more.