It seems like there's been some astro turfing about this in the last few days, it is becoming a popular Liberal talking point. Slavery was outlawed back in the 60s, but Saudi outlets claim the Houthis family has 1,800 slaves and wants to expand the practice. Slavery and human trafficking is an issue because of the extreme situation of the people, after 8 years of relentless bombardment the human rights situation is not what most people would consider ideal.

Slavery does seem to be an issue, and I am not sure how Ansarallah views it.

But this is why critical support is a very important principle. We can cheer the actions people actively fighting for Palestinians, without saying we agree with everything that they do. Churchill hated Stalin's guts and vice-versa iirc, but they were willing to work together to defeat the greater enemy.