A year before the "Momo Challenge" was even a thing that anybody was talking about, my wife and I made the decision to delete both the YouTube Kids and YouTube apps from our cell phones.
Our decision was two-fold. First, our then three-year old boy had become dependent on his "videos" with which he would zone out for as long as allowed watching video after video about toys and cartoons. That's a problem in and of itself but then we started to hear weird sounds, sounds that don't normally belong in cartoons coming from what he was watching on YouTube Kids. To our surprise we discovered that he had stumbled into videos featuring cartoon characters cutting each other's heads off and performing other adult acts, just put to the visual or a dark cartoon. It was disturbing enough for us to yank the app right away and do our best to ween him off that habit.
Fast forward a year and we started hearing about the "Momo Challenge" and YouTube kids apps being hacked telling kids to eat their parents "candy pills" and to turn on the gas stove in the middle of the night. It obviously didn't sit well with us and was too close to home with our experience a year back.
The "Momo Challenge" in and of itself is simply people targeting suicidal tendencies that may already exist within at risk individuals. Where the YouTube Kids app comes in, is that these Momo directives are being inserted into the middle of Peppa Pig episodes on the kids app and are accompanied with threats that if the kids tell their parents, Momo will come after their family. There's reports that it's infiltrated Fortnite systems as well.
It's incredibly disturbing, very unsettling and I can speak to it firsthand, it's very real.
Make sure you're monitoring your kids' use of apps and games.