According to Google's IPv6 adoption statistics, more than 30% of the Internet users are using IPv6 in 2021. In some countries, like France and Germany even have adoption rates over 50%, which makes it essential to adopt IPv6 on your website for international users.
I recently had a very weird issue with Nginx serving static content. A Latin-script letter  keeps showing up in one of my CSS files, and the letters are not in the actual file. It turns out that Nginx doesn't set chartset by default, that's why the characters not in the ISO basic alphabet got decoded to something else.
Nginx came with a rate limit module called ngx_http_limit_req_module, which is quite handy for throttling harmful requests like DoS attack. And the module uses the leaky bucket algorithm to handle the connections. It could allow a certain amount of burst requests in a short period of time to suit the use cases.