I think since taking dex I have noticed the same thing. I appreciate that it helps me function and get through day to day tasks but I have noticed my emotions seem flatter. Like my zing has been removed. I’ve always found light and colour to be extraordinary too yet, for some reason dexamphetamine seems to dull my senses.
I agree also that a lifetime of feeling like we need to suppress, modify or regulate our natural emotions in order to fit in with expected norms can cause a kind of mild depression.