Content-Type header is bogus on encrypted uploads, should be application/octet-stream or similar

[86dd]

Steps to reproduce

1. Try to upload a file in an encrypted chat on a server proxied by lighttpd using mod_proxy
2. 

Outcome

What did you expect?

1. File uploads and gets sent without any issue

What happened instead?

1. Request errors with HTTP 400

Operating system

Debian testing

Browser information

LibreWolf 107.0.1

URL for webapp

https://chat.cat.casa

Application version

Element version: 1.11.17, Olm version: 3.2.12

Homeserver

https://matrix.cat.casa

Will you send logs?

Yes

[86dd]

I have tested cinny, which sends a content-type header set to application/octet-stream and it appears to upload fine. Android SchildiChat also uploads fine.

[86dd]

Element Web: In unencrypted rooms when a content-type header is sent it works fine