Hi @hisunnytang
Welcome to the Auth0 Community!
I apologize for not responding to your questions earlier. Thank you for posting your issue and response from the App Store regarding 18.3.1. We’ve noticed a similar issue, but on an earlier version that was working ok for you (topic with a solution for reference → iOS Application not recognizing Auth0 Associated Domain - #27 by marybeth.hunter ), I will report this internally, and update you when I have more insight.
Thanks
Dawid