You have to replace enable_lazy_ghost_objects: true by enable_native_lazy_objects: true in config/packages/doctrine.yaml :

doctrine:
    orm:
        auto_generate_proxy_classes: true
        naming_strategy: doctrine.orm.naming_strategy.underscore_number_aware
        enable_native_lazy_objects: true
        auto_mapping: true

See https://github.com/doctrine/orm/issues/11950 and https://github.com/doctrine/orm/pull/11853