I am not personally worried about it; I don’t think I’m in the at risk group.
From the people I know in the lucid dreaming community, I have just a couple of reports of people with diagnosed schizophrenia who tried lucid dreaming and it made their symptoms worse. To which the general view seems to be: if it makes your symptoms worse, don’t do it. I don’t have adequate evidence on whether yoga nidra is safe or not; I think a reasonable approach would be to use caution and stop if you start getting bad symptoms.
Also personally, I don’t find sleep paralysis to be a big deal. I know some people are really freaked out by it. But sleep paralysis isn’t the actually risky thing that’s the concern here (the actually risky thing is psychotic symptoms that persist)
Re. Some of the comments… I don’t think I would be distressed if my internal dialog stopped. It’s intermittent anyway, and can switch between auditory and visual. If it just went quiet for an extended while, that would not seem bad. [as a test, just after I wrote that I did 30 seconds with no internal monologue]
I kind of need the internal monolog to write code, for example, so it would be a problem if I could no longer write code in my head.