I am always nervous about the "I ate this and I felt ill afterwards", because it is very easy to overinterpret.
Just two days ago I had a bit of "ill feeling", and was passing gas more than usual. Why? I ate a Chipotle burrito and I haven't had beans in a while. Not having had beans in a while almost always gives me a bit of gas. But if I keep it up and eat beans more routinely, my gut flora adapts and I get a lot less upset and gas.
I have a hard time calling "beans" a dangerous food. Yeah, some people might quibble about phytotoxins or something, but in general it's a food that has been eaten by a lot of humans for a long time and as such how bad it is is bounded; it can't be that bad. But if you use the "does it make me feel a bit ill" stick on it, you can easily get a false positive.
It is not unreasonable to expect to need a bit of adaptation to a new food. If I pay attention, I can notice a similar reaction, albeit on a smaller scale, to a number of cuisines if I haven't eaten them in a while. But it doesn't mean I can judge those entire cuisines as unsafe.
I actually don't post this in defense of the impossible burgers, which I expect are probably a bad idea for other reasons. I just don't think this is a good or reliable measure of that, because it visibly breaks in many other cases where there clearly isn't a fundamental problem.
(Now, if you eat them consistently for a while and it's still a problem, then you do have a problem. And I'm not asking you to do that, because there is no particular need to be able to eat such things.)