I feel like you are referring to the Biden vs Bernie debate where Biden was accused of lying about whether he pledged to cut social security. That’s actually a good example of the limitations of instant fact-checking. Biden at some point during a budget crisis where republicans were proposing scrapping social security said that he thought that temporary freezes in future increases in social security should be on the table. Whether or not that counts as Biden calling for cuts in social security is highly debatable and could not be fact-checked well in the time provided.
Wish CNN did this when Biden was debating Bernie. Just saying. He blatantly lied about wanting to defund social security in the past and the moderators were silent, Bernie called him out on it and he continued to lie. I’d be nice if they had a real-time scrolling headline on the bottom that fact checks the statements they say.