Unable to Remove Expired Certificate on iPhone After Backup Transfer

I am experiencing a persistent issue with an expired certificate on my iPhone running iOS 18. After transferring data from my previous iPhone using a backup, an expired certificate titled "aabenkirke.dk" (issued by R3) continues to appear with notifications stating that it is "Not Trusted." I believe this certificate was carried over from the backup.

I have attempted the following troubleshooting steps without success:

• Updated to the latest version of iOS 18.
• Reset all settings.
• Cleared Safari history and website data.
• Checked VPN & Device Management (no profiles or certificates are listed).
• Attempted a "Reset Network Settings," which did not resolve the issue.

The repeated notifications are disruptive, and there doesn’t seem to be an option to remove this expired certificate from my device manually. I would like to know if there is an alternative solution or if this issue may be related to the backup transfer process on iOS 18.