> How do I stop my kids from getting suckered into an endless scrolling doom loop?

I think the first and best way to ensure this is to not do it yourself.

Pretty much every parent I know does not allow their preteens and younger unsupervised tablet/phone use because the internet is so bad for them at that age. Typically they allow a curated set of content during specific times, and devices are physically removed from the children's environment afterward.