@matigo surprisingly, it seems support is arriving with big sur https://eclecticlight.co/2020/06/29/apfs-changes-in-big-sur-how-time-machine-backs-up-to-apfs-and-more/ though oddly (i think - haven’t spent much time with recent filesystems) it seems not to be using snapshots as part of the remote tm backup?
and local backups switched to snapshots in high sierra https://derflounder.wordpress.com/2019/05/08/creating-managing-and-using-apple-file-system-snapshots-for-startup-drive-backups/
(I had the suspicion I should validate my snark had not expired.)