Bringing up gamers telling each other to kill themselves (sometimes genuinely, although they wouldn’t admit they were actually that angry) is not the gotcha you think it is.
Why dont you engage with what the person you are replying to is actually saying instead of grasping at straws.
https://vegfaqs.com/vegan-sources-of-vitamin-a/
I picked the first resource off duckduckgo, read through most of it and it lines up with what I had thought.
And then here is about b12:
I think its possible you meant b12? Its not found naturally in anything besides meat from my understanding but it is synthetically added in some common vegan staples like alternate milks
The point is that you are asking the wrong question sort of. If we only accepted physical remnants of someone or their life to prove they exist, Jesus wouldn’t be the only one we would have to throw out.
Not to say I know how to prove stuff historically, it does sort of seem like magic sometimes. If we found out today that carbon dating was off by a magnitude I would not be shocked, so that’s all the faith I have in it due to my bad understanding of it.