The "joke" is the gender dysphoria goes so far that a trans person would believe they are able to get pregnant.
This is considered a hot take on social media, but gender dysphoria is a mental disorder. But so is ADHD, it being a mental disorder doesn't make the symptoms any less real, or mean that people should treat them any differently. The best treatment for the dysphoria is generally to transition to the desired gender and talk to a therapist before, during, and after. Most people who use the montra "trans women are women" understand that being a trans woman is not the exact same as being born a woman and there are many limitations that come with transitioning to the desired gender. One of which is that trans women do not have a womb and cannot bear children.
There is a very small percentage where it goes too far and they believe they were actually born a woman, they believe they have a womb, need to use feminine hygiene products like tampons, etc.. This is no longer strictly gender dysphoria, but a delusion disorder which may or may not coincide with gender dysphoria. Imo people in this state should not be allowed to transition without the close guide of a doctor and a therapist, because likely they will still experience strong dysphoria after transitioning until the underlying delusions are addressed.
The joke sees all trans people as the second set, when they are actually an incredibly small percentage.
You are completely wrong about the way gender dysphoria works. It's the opposite, we have euphoric feelings and comfort in the gender we move towards, Gender dysphoria is the opposite feelings we get when we repress that and are forced to express ourselves as the wrong gender.
Gender dysphoria is a diagnosis and a mental health crisis, but it is alleviated by transition, meaning of largely goes away when we transition.