MariaDB Multi-source Replication SQL_SLAVE_SKIP_COUNTER
Change the default_master_connection variable for the session to make it work for a specific multi-source connection:

STOP SLAVE 'src1';
SET @@default_master_connection = 'src1';
SET GLOBAL SQL_SLAVE_SKIP_COUNTER = 1;
START SLAVE 'src1';
SET @@default_master_connection = '';