rsync gives protocol version mismatch on clean shell WSL->Debian

I’m in a WSL bash shell trying to rsync to a remote cloudcast machine (Debian) over ssh. However, I keep getting protocol mismatch error.

Some research turned up that the most common cause for this is an unclean shell, i.e.: a shell that prints something when logging in.
In the remote machine, I added .hushlogin to the user home, and I also added PS1=”” to .bashrc to get rid of the prompt (per some post somewhere).

Testing for a clean shell shows it really is clean. The following logs in without any messages or even a prompt:

ssh -tt -i ~/id_rsa -F /dev/null -oStrictHostKeyChecking=yes -oUserKnownHostsFile=/mnt/c/Users/anonyuser/AppData/Roaming/GGP/ssh/known_hosts [email protected] -p 44722 --

The following shows log.out is created with 0 bytes:

ssh -tt -i ~/id_rsa -F /dev/null -oStrictHostKeyChecking=yes -oUserKnownHostsFile=/mnt/c/Users/anonyuser/AppData/Roaming/GGP/ssh/known_hosts [email protected] -p 44722 -- false > log.out

And yet this:

rsync -a -v -e "ssh -tt -i ~/id_rsa -F /dev/null -oStrictHostKeyChecking=yes -oUserKnownHostsFile=/mnt/c/Users/anonyuser/AppData/Roaming/GGP/ssh/known_hosts [email protected] -p 44722 --" lol.txt [email protected]:/home/cloudcast/

gives the protocol mismatch version.

Running with -vvvv shows this:

(Client) Protocol versions: remote=1752392034, negotiated=31

I’ve tried adding -q and/or -2 to the ssh command, per some other post somewhere, but no difference.

I checked the rsync versions, and they’re the same in the remote and local machine:

rsync  version 3.1.2  protocol version 31
Copyright (C) 1996-2015 by Andrew Tridgell, Wayne Davison, and others.
Web site: http://rsync.samba.org/
Capabilities:
    64-bit files, 64-bit inums, 64-bit timestamps, 64-bit long ints,
    socketpairs, hardlinks, symlinks, IPv6, batchfiles, inplace,
    append, ACLs, xattrs, iconv, symtimes, prealloc

The local ssh version is:
OpenSSH_7.6p1 Ubuntu-4ubuntu0.3, OpenSSL 1.0.2n 7 Dec 2017

The remote ssh version is:
OpenSSH_7.4p1 Debian-10+deb9u3, OpenSSL 1.0.2l 25 May 2017

Any ideas on what’s wrong?