Repercussions? This is nothing new in china, any dissent is being censored, scrubbed and the person that put it out there arrested/disappeared. If that person is lucky, they get to make a retraction and return home under observation of the internal security apparatus and different limitations. If they are less lucky, they get imprisoned for a long time with only a formal trial. There are other even worse outcomes that I will not speculate on here, but let’s just say they are grim.

“Social credit” has never been this single unified omnipresent score, but it is true that the Chinese government can easily make people miserable. A while ago, some protestors were given a “Red Code” for the COVID control app. Because a green COVID QR code is required to enter basically any public place in China (even taking a bus), this effectively made them social outcast. And these were just people protesting against real estate developers who went bankrupt and the local government, without challenging the regime in Beijing. Anyone who dares to protest against Xi Jinping and the communist regime (like the guy on the bridge in Beijing) can be assumed to be jailed and tortured, maybe even executed.

Social credit never got rolled out at a national level from what I understand. It was only trialed at a few cities.

Yes. If you're score is too low, things like the subway, accessing your banking, using apps, all get blocked. As your social credit is attached to all of that. Afaik, Weibo is a pretty all encompassing app