Can't activate encrypted messages on my phone - says my paper key is incorrect or the key pair is incorrect

I’m the owner and admin of the site. I mean, I own the server root access.

Don’t even know what to look for. Any ideas?

I just tried in a different browser (Safari, while my main browser is Brave), and the “activating another device” worked just fine.

So looks like it is specific to my iPhone. But I don’t know what can be the root cause.

Can my iPhone’s Lockdown Mode be the reason?? What feature would it turn off that would prevent encrypted messages from working in Discourse?

NOTE: The Discourse instance domain is added as an excluded safari website in the “lockdown mode for websites” section in the Lockdown Mode section. So the site should not be affected by the lockdown mode I guess.