I had to lookup SSC. I think this annual report footnote means that Facebook could be found in non-compliance of GDPR or other regs and could chose to abandon the market rather than pay the fine. Or based on [1] they could apply the EU SSC standards to their businesses outside the EU and be in compliance and continue operations.

https://eur-lex.europa.eu/eli/dec_impl/2021/914/oj?uri=CELEX...

[1] > In order to provide appropriate safeguards, the standard contractual clauses should ensure that the personal data transferred on that basis is afforded a level of protection essentially equivalent to that guaranteed within the Union (10). With a view to ensuring transparency of processing, data subjects should be provided with a copy of the standard contractual clauses and be informed, in particular, of the categories of personal data processed, the right to obtain a copy of the standard contractual clauses, and any onward transfer. Onward transfers by the data importer to a third party in another third country should be allowed only if the third party accedes to the standard contractual clauses, if the continuity of protection is ensured otherwise, or in specific situations, such as on the basis of the explicit, informed consent of the data subject.