Is veganism and atheism related to each other?

some people are vegans because they believe it’s healthy, I know an older diabetic who was having trouble keeping his blood sugar low enough till he went vegan.

Atheism isn't a belief system but, rather, a lack thereof.
Perhaps the reason atheists are more likely to be vegans is because they do not have the specific belief that God made these other animals to be eaten.
Perhaps a lot of religious people have a gut feeling that eating animals isn't right, but they are consoled by the belief that God made these animals specifically to be eaten by humans.
That said, it's possible to be an atheist who believes that we are omnivores and that us eating meat is no more morally wrong than dogs eating meat or bears eating meat, etc. But a religious person could have that reason, too, for not being a vegan.

Probably no in most cases since many (most) vegans.vegetarians do so for spiritual reasons

Literally all the vegans I know irl are Christians (more or less observant, but defo not atheists)

Most vegans I know are vaguely spiritual or something.

Yes I have met people who believe in God and are vegan.
Many Hindus are vegan.
My sister in law and brother in law are devout Christians and they and most of their church are vegan. (yes vegan not vegetarian)

In terms of crazy yes 🙂

I'm religious, though not an Abrahamic religion and I'm vegetarian.

I haven't seen a connection