As somebody with a bit of learning on the matter (it's amazing the hats you have to wear to prove you deserve to live - from anthropologist to biologist to archeologist), it's interesting to see how the language of the community has evolved as our scientific understanding of sex vs gender has.

The term started as transsexual, and there are older people who refer to themselves by that term, but by the 2000s the term had shifted in favor of transgender, noting the recognition that sex doesn't equate to gender that happened around that time.

Then came the use of cis as well as AMAB and AFAB (assigned male/female at birth) in order to better describe the complexity involved around the fact that a doctor has to declare you one gender or another when you're born, and the easiest way to do that with the highest likelihood of being correct is based on sexual characteristics - namely, what genitalia you have. So cis is used to describe people who have no reason to disagree with the doctor's assessment, and there's a lot of discussion around where intersex people fall in the community (do they fit in the trans umbrella term?).

People like Dunning-Kruger up there are basically arguing that isotopes don't exist.