Fellow LDer here. I've never felt any adverse effects of the type in discussion (quite the contrary, amazing euphoria and well-being on some occasions). But we shouldn't pretend that lucid dreaming is likely to be stimulating only and exactly the same brain regions as more typical dreaming (in terms of the metabolic and other activity levels). Learning to activate the relevant memory writing modules while in dreams so as to increase dream recall is, after all, one of the typical first steps to developing LDs. That mental machinery is seemingly not typically on to such a degree when dreaming as most people normally do.

That alone shows that some brain activity needs to be online that isn't in typical dreaming, and I imagine the various other bits of learned mental behavior to the LDing skill-set also change activation levels in brain regions. Learning to exert the kind of attention/expectation control to stabilize and alter dreams is another sub-skill that often takes practice and so probably involves bringing online brain resources that might otherwise be off/recharging.

So if some people have lower neurochemical reserves of some type or other, this extra activity, use of such neurochemicals, at night (when their reserves would otherwise be replenished) could push them under some threshold of good functioning for a while. My guess is that such sensitivities would be the rare minority cases, but this field is quite understudied to have grounded empirical beliefs on the matter.