These are policy-driven snapshot management and replication tools which use OpenZFS for underlying next-gen storage. (Btrfs support plans are shelved unless and until btrfs becomes reliable.)
It's a wontfix for me personally, but if the same thing can be accomplished with <5.26-friendly code without too much trouble, I'd accept a pull request.
This may be a wont-fix, given how close we are to EOL for RHEL7, but this commit: https://github.com/jimsalterjrs/sanoid/commit/c4e70280225f7b3ec03cc075daf218dde468412f introduced a Perl 5.26-ism in the use of `<<~' for Heredocs on line 643. This makes current syncoid fail to run on RHEL7 and derivatives that shipped with Perl 5.16.3.