Vegangender is a xenogender tied to/influenced by one's veganism or vegan activism. It could be that the fight for animal liberation has become a core part of someone's identity that it's become part of their gender(s) as well.
Flag
The vegangender flags were created by Mod Hermy of pride-flags Deviantart archive. They are based on the vegan flag created by Gad Hakimi.[1] and the queer chevron flag. The chevron was chosen instead of basic striped flag to look more similar to the original vegan flag while remaining distinctly as a LGBT flag. The V with a leaf symbol is a symbol commonly used by vegans.