The notion of FB abandoning a market of 500m comparatively rich people just because they can’t shuttle data around seems rather absurd to me
Now there is an issue with the extraterritorial overreach of the US CLOUD Act, which means the surveillance dragnet is extended to any US company, even if the data is hosted on servers outside the US. A strict reading of GDPR and Schrems II would mean that it is actually unlawful for Facebook to offer services in the EU.