The decision goes further than a fine, though. It orders Meta to stop transferring personal data of people in the EU to the US.

How is this actually supposed to work in practice, other than sharding EU and non-EU customers and having them unable to communicate across the shards?

Meta’s chock full of very smart, highly paid people. I’m sure they’ll figure something out.

Why unable to communicate? Is there any reason why the relevant non-EU customer data cannot be stored within the EU as well?

If someone in the US visits a profile page of someone in the EU, that necessitates a transfer of data outside of the EU.

Perhaps that's an extreme and pedantic example though.

Confidential Cloud computing is the answer and hyperscalers work on that. You literally put your data in a black box.

Facebook has made approximately 20 billion in profit yearly for the last 5 years. They don't break down profit by country, but EU represents a small portion of users. About 10% overall. Speculating that overall profits are 2billion from EU means that the fine represents about 5% of profits.

Not that bad

Note that in the last 5 years (since GDPR came in), Facebook has also been fined €405m, €390m, €265m and €225m on other occasions: https://www.politico.eu/article/eu-hits-meta-with-record-e1-...