Hello, thanks for support.
It was hosting config, one call with the support and that's it.
For information, with IONOS the config is a little bit weird. You have to rename the file php.ini (at the root of the site) to .user.ini to populate the php config in all directories of the site web.
I'm going to renew my subscription in couple of week to prepare J4 migration.
Thanks again.
Jean-Marc