If the users you’re sharing with are logged in, chunking is used so it is mostly a non-issue (other than timeouts sometimes needing adjustments if you’re using an external reverse proxy).
If you’re sharing with users that are not-logged-in in <= v30, chunking is not supported so uploading large files will be more dependent on a variety of parameters throughout the end-to-end path.
If the currently in beta v31, chunking is supported for public uploads.
However, in your case, your biggest problem is probably this:
See AIO: Notes on Cloudflare (proxy/tunnel)
Cloudflare limits HTTP transactions to 100 MB.