Walter Bushell wrote:

And here¹s another useful fact: since grain proteins (especially
wheat) contain a lot of glutamine (hence ³glutamine peptides²),
heavily hydrolyzed vegetable protein is often a way to sneak MSG into
foods without listing it on the label.

Glutamates other than MSG are also called "natural flavors".

Something I wonder about with respect to glutamates - The "fifth taste"
of unami appears to be detection of glutamates. If glutamates are bad
for us how did we evolve an actual taste for them? Perhaps MSG in
specific is problematic but other glutamates not so much?