The EU authorities themselves are not banning Facebook, per se, despite the headlines - the threat to remove Facebook from the European market comes from Facebook/Meta, because they don't want to comply with the expected upcoming order preventing them from transferring EU data subject data to the US. The thing that the EU officials are preparing could be described as a ban on data transfer, although it's really an order to comply more correctly with an existing law (the GDPR) rather than a new obligation. But it's not a ban on operating in the EU.

If Facebook kept EU data subject data in the EU, or even if they use Standard Contractual Clauses to transfer it to different third countries without the same kind of problematic surveillance laws that the US has, there would be no issue.

Well, allies can ask friendly governments for information on their own citizens without violating and of their own privacy laws. So it can be useful as a circumvention tool for them.

If a major war occurs in the near future it won't be between the EU and the US. This lowers the risk of US companies hold EU data.

Also, don't be one sided on this. The EU countries also spy on the US.