Could be a statistical thing given that they are so popular now? There is certainly a lot of hype on the internet about it but no real consensus about the risk being any higher than is inherent with escalators

I don’t know how they could pose any more of a risk than other footwear such as thongs, sandals or even joggers. I'm not sure that specific warning signs about this specific footwear should be posted (as others have done) as that could inadvertently condone wearing all other potentially higher risk footwear like thongs. Much comes back to correct design & maintenance of the escalators and parental control.

Should also ensure that the standard safety warning signs are in place. One child safety site I saw recommends carrying children on escalators which I think is a much greater risk.

I think the generic warning signs (hold Childrens hands, keep away from edges etc) are probably sufficient as long as they are in place, obvious and in good condition.

Having said that, you should monitor the issue and reassess your position if required