looks like the check thd->wsrep_exec_mode==REPL_RECV in is_client_connection() fails for wsrep applier (wsrep_exec_mode is for some reason LOCAL_STATE) and it is closed as a client connection.
While it is not entirely clear why wsrep_exec_mode in applier is LOCAL_STATE, adding a check for thd->wsrep_applier seems to fix this particular situation.
looks like the check thd->wsrep_ exec_mode= =REPL_RECV in is_client_ connection( ) fails for wsrep applier (wsrep_exec_mode is for some reason LOCAL_STATE) and it is closed as a client connection.
While it is not entirely clear why wsrep_exec_mode in applier is LOCAL_STATE, adding a check for thd->wsrep_applier seems to fix this particular situation.