Noticed warnings written to mysqld.err log file:

2022-12-05 18:49:34 33 [Warning] Unsafe statement written to the binary log using statement format since BINLOG_FORMAT = STATEMENT. Statement is unsafe because it uses a system variable that may have a different value on the slave Statement: OPTIMIZE TABLE `table1`

According to the warning, it appears due to having "BINLOG_FORMAT = STATEMENT". However, in fact binlog_format = ROW is set in configuration file, also corresponding variable value is correct.

mysql -e 'select @@binlog_format;'

@@binlog_format

ROW

Since we don't use bin_log replication, this warning doesn't affect anything. However, it's a bit strange to get it on galera cluster members.