Jeremy Bailenson’s Virtual Human Interaction Lab at Stanford has been researching the effects of VR experiences on children. Below is a CBS video (from 2015) that talks about it.
Key soundbite: after kids experience something in virtual reality, 50% of them say a week later that it actually happened in the physical world.
That factoid can sound shocking, but I haven’t read the papers and don’t claim to know all the context and how meaningful or concerning it truly is. And of course even adult memory is famously unreliable (see: The Invisible Gorilla for a good discussion of that and other psychological illusions).