Certainly, but when you make a comment or post it gets transferred to all federated servers without your express consent and you currently can't permanently delete anything.

By that logic though all of Fediverse is illegal and should be shut down. There is significant work to be done there, not just by Facebook but by the Fediverse community on the whole.

Ah yeah if the originating instance sends data to a secondary one then that is somewhat different.

The originating instance definitely cannot be held responsible for failing to force a separate instance in another country to delete its cached copy of user data imo. I think what is more likely is that EU courts could force European Jimmy instances to only federate with GDPR-compliant instances.