Setting `proxy-request-buffering off` leads to removing original `Content-length` header

I noticed that Nginx ingress caches big requests and I found that such behaviour can be switched off by nginx.ingress.kubernetes.io/proxy-request-buffering: "off" that in terms of Nginx is equal to proxy-request-buffering off

After that I started receiving no Content-Length header on my server side although it is sent on the client side

Is it expected behaviour? Can I receive the original Content-Length?