The supposed campaign on tiktok ran days before the election. It is remarkable for state organs to be able to act within a week or so. Annulling the election in this situation seems the right thing to do. A similar cancellation of results happened in Austria in 2016. A year later it indeed would have been too late.
No, the supposed campaign started one month before the elections. It ramped up maybe in the last few days before the election. But you don't convince 2 million people to vote for a crazed maniac like CG in two days of manipulation.