OK. Thanks for ur help. (:з)∠)

It's Quantumult X, a VPN app from a third-party developer. I’ve seen similar reports from other users, so this isn't an isolated issue. It’s not just Quantumult X; other VPN apps are also affected. The earliest feedback I found was from June, during an iOS beta (I'm on iOS 18.0). Some say it might be a Safari issue, but using Chrome to install the certificate didn’t work either. So far, the only solution my friends found is to roll back to a previous iOS version. Thanks!

It's Quantumult X, a VPN app from a third-party developer. I’ve seen similar reports from other users. It’s not just Quantumult X; other apps are also affected. The earliest feedback I found was from June, during an iOS beta (I'm on iOS 18.0). Some say it might be a Safari issue, but using Chrome to install the certificate didn’t work either. So far, the only solution my friends found is to roll back to a previous iOS version. Thanks!