foreign data wrapper connexions from postgresql

Hi

i'm facing an issue with Postgresql11 using the mysql foreign data wrapper connection to a remote Mariadb Column Store database (10.2.10-MariaDB-log Columnstore 1.1.2-1)
Requesting a simple select on a foreign table the error message is

postgres=# select * from mysql_foreign_table1 limit 5;
ERROR: failed to execute the MySQL query:
Commands out of sync; you can't run this command now

the select is still requesting on the MariaCS server until the PG session is closed

i'm in trouble to see that this select runs well with this environment:
PG11/debian Stretch

but not with:
PG11/debian Buster
PG12/debian Buster

A Mysql client on the PG server requests with no issues in all cases

Thanks a lot

Emmanuel