Thanks! I can see that there is a “wider” redirect in place, which is interfering with the one you intend:
from = "/*"
to = "/.netlify/functions/server"
status = 200
(the one you intend is just after it - but is never reached!)
I think that is a “standard” route added by our nuxt framework support, that is required, so you don’t want to remove that.
And, as to why your redirect does work when you put it in _redirects, we prepend_redirects to your configuration so it’ll show up before that default route; redirects from netlify.toml is added only at the end - after our automagic route - and is thus overridden.