Did my periodic OS upgrade today, and one change that has had an (easy to fix) impact on my backup system is that OpenSSH 9.0 is phasing out the special protocol that was used to implement the scp command, in favour of using the same one as for sftp. One difference this makes is with file specs that contain shell-special characters (e.g. spaces). Previously, when specifying such to the scp command in the shell, you had to do two levels of escaping, one to get them past the local shell, and another to work with the remote shell. But now, the second level of escaping for the remote end is no longer needed. The release notes describe this second level of quoting as “finicky and brittle”, so all in all things are simpler without it.