Something else to think about, these are not the
menthol cigs from years ago.
I heard some clerks talking about them and they use
some kind of capsule that is broken to release the
menthol, they had a name for them but I don’t recall
what it was.
I quit 35 years ago.
Most likely a spray encapsulation of the menthol that melts as the ember approaches it releasing the menthol for vaporization. Old technology. Could do the same in the filter - just squeeze the filter to burst the encapsulated beads to release menthol. Encapsulation compound would be a lipid, wax, or polysaccharide. There is nothing new under the sun.
Camel has a type called the ‘Crush’ that has a crushable menthol capsule in the filter. There may be other brands as well.