Personal anecdote from cooking for years for a variety of people of varying intelligence, background, and countries:
Most people claim it gives them headaches and nausea.
They "know" this because they feel it every time they eat (american) "Chinese food"
Not a single one has ever had either symptom after eating my cooking that has a little sprinkled in.
Now, I have tried to prove a point to some by informing them (many hours after the food, and asking about how they feel) that they in fact ingested MSG without issue and had no symptoms, usually to rounds of spontaneous nausea and headaches that had apparently gone unnoticed for hours until just then.
It could be that ingesting a shit-load of greasy, oily, carbs and over-eating that caused their nausea and headaches when they gorged themselves on "Chinese" food, but no, they know it's the MSG.

As usual, I'm left wishing I had the money for an EV.
Yes, ideally I'd rather be able to use my bicycle and cargo trailer for shopping and public transit for work, but thats literally nonexistent.