a) Biden, the Clintons, Pelosi, Schumer, Kerry, much of the MSM, etc. have been totalitarian communist traitors who want to destroy America for decades, possibly trained by commies during the Cold War era. However their plan was to wait until the time was right for Marxist revolution and otherwise wear the mask of a moderate politician. Their support for things like LGBT and environmentalism was always a long term play to get this point.

b) The Democrats 10-15 years ago were just normal stable moderates, still corrupt and warhawks, etc., but not commies. They genuinely believed in things like helping the environment and legalizing gay marriage. However they became part of the woke cult and underwent a psychological shift when the rest of the left did sometime in the last decade. As a result their brains have been hijacked at this point causing them to now be malicious totalitarian commies.