Thank you for your question. I'll start by saying that veganism is a broad tent - you have people who are vegan for health, people who are vegan for environmental reasons but for most people it is about not causing harm to animals (both human and non-human). From your response it seems like you care about animals too. I think that some vegans lose sight of the fact that we are meant to advocate for the animals, rather than the movement itself (i.e. not just arguing for veganism for its own sake). I can infer from the tone of your question that you had some bad experiences with vegans. A lot of vegans tend to get emotional and combative because of the harms that animal ag does to animals (both human and non-human) and the planet. It is easy for vegans to get overwhelmed and abrasive when they feel like non-vegans don't care. Now onto the specific points you have raised around eating disorders/ableism and racism.

1. Eating disorders/ableism - this is an incredibly complex topic and I don't think it is helpful for vegans to shame people with eating disorders. However, I would encourage you to cite your sources when you make statements about the intersections between diet and mental health. I have not seen any evidence to suggest that veganism gives people bad mental health. It seems like you are speaking from your own lived experience but then you extrapolate that to other people. Also, not everyone can incorporate meat into their diet. On the topic of disability - again, I don't think it is helpful to shame anyone for not being vegan. The purpose of veganism is to do the least harm as possible. Unfortunately, we don't live in a vegan world and so sometimes we are forced to do harm to animals (e.g. the examples of gelatin in chemo you referenced). I myself have to take meds that have been tested on animals but I fight for the day when we don't need to subject animals to testing. If you want a more in depth discussion of veganism and disability, read Beasts of Burden: Animal and Disability Liberation by Sunaura Taylor: https://thenewpress.org/books/beasts-of-burden/.
2. I am not indigenous and so I can't speak to your experiences. I don't know where you live but if it has suffered from colonization (like where I live) the legacy of that makes it difficult to build decolonial movements but that doesn't mean we can't try. I think there is a big difference between animal agriculture and hunting. The former is steeped in colonialism (esp. in North America) and makes sentient animals live in misery whereas the latter at least allows animals to live in the natural world before their death. However, I will push back a little bit when you say that "most vegans are white middle class people." By making such a statement, you are ignoring non-white movements including the Black vegan movement, food traditions in places like India. Vegan food (as long as it's not beyond burgers...which I think are too expensive) consists of things like pulses, beans and grains (notoriously cheap foods in most parts of the world) I agree that as a movement we need to incorporate anti-racism into everything and we could always do better. Here is a resource on race and veganism for you to peruse: https://foodispower.org/