Is it because of their high dividend yield?
Is it because their dividend growth rate has been aggressive during the past few years?
Is it because Buffett sees Citi's turnaround strategy looking to bear fruit in the near future?
According to a Motley Fool
article:
"Citigroup is making the hard but seemingly right decisions in selling these international consumer banking operations...It could also leave a revenue hole at the bank. Additionally, rising expenses have hurt Citigroup's performance and near-term outlook, but it seems that management is finally spending the necessary amount to correct regulatory issues that have dogged the bank for years."
That quote is what I see to be an answer to the third question.
As for the answers to the first two questions, Citi's dividend yield is currently at 4.10%. As for its dividend growth rate, the company went from paying $0.01 per quarter in 2013 to paying $0.51 per quarter in 2022. Though Citi's dividend hike history has been all over the place, overall, the company has hiked its dividend aggressively over the past 9 years.
Here's a link to Citi's dividend history.