It for sure happens.
Most people are genuinely shocked to learn that one can be allergic to veggies, but that is often the result of a cross reactivity to some kind of pollen in a similar plant family.
OTOH, you could have a mast cell disorder and something besides an allergen is provoking an allergic type response.
Look up MCAD - Mast Cell Activation Syndrome
That’s what I have been diagnosed with and I can’t eat any veggies. I react to them all.
Thanks for feedback. It’s amazing how the body can change over the years. I will have to bring this up with my allergist.