If you somehow still considered uploading your face/ID to Discord, here's one more reason not to: Peter Thiel seems to be the lead investor in the service that implements the age check. And, oh, the service page says they will store our data on their side (at least for a little while).

https://www.pcgamer.com/software/platforms/oh-good-discords-age-verification-rollout-has-ties-to-palantir-co-founder-and-panopticon-architect-peter-thiel/