Those Austrians who are concerned about their personal data they provide for the purpose of age verification leaking are overreacting. There is no reason to worry.
That's because a subsidiary of the Austrian Broadcasting Corporation (#ORF) already leaked every single Austrian's birthdate a few years ago, so your data is already out there. The Austrian data protection agency stated that that company "did everything right“, and there were no repercussions.
I am being sarcastic, of course. When you upload a copy of your personal id, keep in mind that the company processing it will face little to no consequences in case they leak that data. So there isn't much of an incentive to waste much money on protecting it. Also, don't expect any compensation from that company (how much did you get from #equifax?) in case you incur any damages because of that leak - the onus will be on you to prove that the damages are a direct consequence of that specific leak.