The Houthis are engaged in a Saudi instigated and backed civil war within Yemen, they are NOT attacking or likely to attack Qatar, the UAE, certainly not Shia dominated Iraq, Lebanon or even Israel.
The REAL reason Americans are being advised to leave the region is because Trump's blackmailer (Yeeha) is ordering him to hit Iran's Nuclear facilities again before the Israeli election in case he (Yeeha) gets ousted. If or when that happens, then yes American bases in those Countries will be at risk of Iranian (not Houthi) retaliation.
The REAL reason Americans are being advised to leave the region is because Trump's blackmailer (Yeeha) is ordering him to hit Iran's Nuclear facilities again before the Israeli election in case he (Yeeha) gets ousted. If or when that happens, then yes American bases in those Countries will be at risk of Iranian (not Houthi) retaliation.