“Draining the swamp” in the political context is referring to gutting public safety nets like SNAP benefits, affordable healthcare, and government safety oversight so they can give the wealthy tax breaks. The swamp is the working parts of government being demonized as if supporting the general public is not a useful ecosystem.

That description is what Repiblicans said it meant, but what I wrote is what they actually meant based on every single thing they have done while using the phrase. Like how they say they want to enforce fair elections while suppressing the vote and claiming there is widespread voter fraud despite decades of evidence that it barely ever happens.