Hello all, I have replied to Daniel at #897950 (https://bugs.debian.org/897950) Discussions about migrating curl to libssh will follow there.
With regards to the libssh-dev build-dep, I have readded it to curl as 7.80.0-3 and Ubuntu will be able to sync again. Note that 7.80.0-3 is not using libssh other than as a build-dep, Debian's curl is still linking against libssh2, it's only on Ubuntu and onwards that they're using libssh. Thank you everyone. -- Samuel Henrique <samueloph>