Warring theocracies. Houthis are a cultish, nominally Shia minority in Sunni majority Yemen. They're trying to impose a Houthi theocracy and force the Sunni majority to become Shia (with Houthi cult aesthetics). Iran, which is majority Shia, gives them weapons and money.

Saudi Arabia is a Sunni theocracy and doesn't want them to do this, so they give weapons and money to their Sunni opponents.

>they give weapons and money to their Sunni opponents.

Understatement of the year. The Saudis ran a multi year bombing campaign that killed tens of thousands of civilians, with direct US support (including mid-air refueling and “targeting”). On top of that, the Saudi/US coalition created a famine via blockade that likely starved 50k children to death. Were the Houthis backed by Iran? Sure. Were the Saudis and their former puppet government in the capital not backed by the US? And they still lost.