cloudflared: 🐛 FTP data transfer fails

Describe the bug

Transferring files via FTP over WARP client and cloudflared causes data loss.

Using Cloudflare Zero Trust + WARP. On Cloudflare Teams web I created a new tunnel with defined private network, installed cloudflared on a local server and WARP client on a local client machine. The client machine (Windows) is connecting via WARP to cloudflared on the local server which proxies the traffic to a third server.

Other services (HTTP, HTTPS, RDP, MSSQL) seems to be working correctly except FTP data transfers. The FTP connection is successfully established but file transfers produce connection errors and files are transferred incomplete or with a corrupted content.

Expected behavior

Files are transferred correctly.

Environment and versions

• OS: cloudflared on Windows Server 2016 and on Amazon Linux (same behavior); WARP on Windows 10
• Architecture: AMD
• Version: cloudflared 2022.7.1, 2022.6.3, 2022.4.0 (same behavior); WARP 2022.7.421.0

Logs and errors

There is no error in cloudflared log. For each transfer I can see

2022-08-03T15:24:13Z DBG tcp proxy stream started flowID=d1f1c6b9-31bd-4609-b24d-56fafb24400f
2022-08-03T15:24:13Z DBG tcp proxy stream finished successfully flowID=d1f1c6b9-31bd-4609-b24d-56fafb24400f
2022-08-03T15:24:13Z DBG origin->tunnel copy: read tcp %local%:63576->%remote%:49314: use of closed network connection

However the same DBG message is logged also for successful transfers and also for other services (e.g. MSSQL).

I tried protocols http2 and quic, no-chunked-encoding but did not help.

Additional context

Tried several FTP clients (Total commander, WinSCP, FileZilla), FTP servers (both Windows and Linux) and client computers. Everything has the same issue.

Is there a configuration which could help? Or any other more advanced debugging option?

Thanks a lot!