The GDPR doesn’t apply only to services hosted in the EU, but any services handling the data of an EU citizen.
This is why some news outlets in the US just decided to block EU users all together, out of laziness.
IANAL, but the GDPR doesn’t cover pseudonymous data. Actually the GDPR encourages data processors (= services) to use pseudomization.
Personally identifiable information are IPs, email addresses, street address, name, date of birth, … Lemmy only collect IPs and email addresses. And these are not shared between instances.
Whether the service is hosted in the EU or not, as long as it serves EU users, lemmy should provide a way to delete emails and ip information in a self serving way. (maybe by deleting the account) In the mean time, instances admins have to fulfil requests to delete emails/ips of EU citizens from the database.
As I said in another comment, the GDPR protects people. And the GDPR only applies to personnaly identifiable data (IPs, email addresses, street address, legal name, date of birh…) Lemmy only collect emails and IPs, and do not share them between instances. So it’s very easy to comply to the GDPR as long as you don’t do anything shady.
The EU has a marketing issue. They tried to pass legislation to prevent companies to collect data. But instead, company displayed a popup, kept collecting data, and blamed it on the EU. Everytime I see a popup, I blame ruthless data collection.
Actually, Lemmy is most likely violatiing the California Consumer Privacy Act, which, as opposed to the GPDR, gives the right to update/delete any data generated by the user, not only personally identifiable information.