Recent development that the main reason why south areas like Kherson fell so quicky is because Ukraine had traitors in their general ranks that aided Russians
https://mailbd.net/news/the-presiden...raitors-46997/
https://twitter.com/user/status/1509652316533792773
Most notable Kherson was given with barely a fight which is counter to the fact that it was near Crimea and should have been well defended. These acts of treasons heavily contributed to Mariupol's current situation.
It was also been known that one of the main reasons why Putin thought that Ukraine would be easy pickings, is that he tasked the FSB, most notably Beseda and his deputy, to bribe Ukraine officials to switch sides at the time of the invasion. The funds were embezzled for years until a faithful meeting in the fall where Putin finally unveiled his wishes to invade Ukraine. They are thought to be the source of how US had such amazing pre-war intelligence that clearly showed they had insider information.
https://twitter.com/user/status/1508092951997595650