cross-platform backup tool openSUSE Leap 15.4: version problem?

Hi Folks,

Longtime rdiff-backup user here.

I've got a couple dozen desktops and servers backing up
to a central server, all running openSUSE Leap 15.3.  Last
week I updated one of the desktops to 15.4 and now I'm
getting rdiff-backup errors.

I vaguely recall that version 2 broke backward compatibility.
Is that true?

Leap 15.3 has 1.2.8
Leap 15.4 has 2.0.5

If this is the issue, is there a workaround?  I've got almost a petabyte
of data floating around on these hosts and I can't instantly upgrade
all of them in unison.

The installs are all from the standard openSUSE repos. Maybe try to
install 1.2.8 on the newer Leap 15.4 system?

Any suggestions?

Regards,
Lew