This is why FB has moved data for 1.5b users back to the USA
[1] https://www.reuters.com/article/us-facebook-privacy-eu-exclu...
This is an indication that they won't apply GDPR globally (for users in e.g. India or Brazil), but they don't have a choice for the EU users.
The discussion is here:
https://news.ycombinator.com/item?id=16872542
I don't see it in a quick scan, but I wonder if that means all the revenue from those countries will no longer be shielded from US taxes, which might indicate how seriously FB see the GDPR as a threat.
EDIT: pdkl95 mentions in another comment, they claim it doesn't.