I think the issue is that there are conflicting studies. Some like this one that has found some people to be glutamate sensitive.

https://myacare.com/blog/part-1-glutamate-sensitivity-real-myths-about-glutamate-msg-and-more

You can also find studies that say there is zero effect. Don’t doubt their results as they never tested me because if they did, they would have a different result. Plenty of other studies have also found some to be sensitive to glutamate so downplaying here might lead someone to dismiss my suggestion which is a real shame as there is Zero harm to cut out high glutamate foods for a period and see how sleep goes.

For me, I absolutely assure you that high glutamate foods really make me hyper. Like zero doubt here as I have experimented a lot with this right down to a teaspoon of MSG with non glutamate dinner that I know has no effect on my sleep to end up absolutely wired for 12hrs as if I slammed 5 cans of red bull and more. It is really awful and while you clearly do not have this issue, I kindly request you do more research before sharing as it is not as black and white as you just presented.