The setting innodb_safe_truncate=ON reduces compatibility with older
versions of MariaDB and backup tools in two ways.

First, we will be writing TRX_UNDO_RENAME_TABLE records, which older
versions do not know about. These records could be misinterpreted if
a DDL transaction was recovered and would be rolled back.
Such rollback is only possible if the server was killed while
an incomplete DDL transaction was persisted. On transaction completion,
the insert_undo log pages would only be repurposed for new undo log
allocations, and their contents would not matter. So, older versions
will not have a problem with innodb_safe_truncate=ON if the server was
shut down cleanly.

Second, to prevent such recovery failure, innodb_safe_truncate=ON will
cause a modification of the redo log format identifier, which will
prevent older versions from starting up after a crash. MariaDB Server
versions older than 10.2.13 will refuse to start up altogether, even
after clean shutdown.

A server restart with innodb_safe_truncate=OFF will restore compatibility
with older server and backup versions.