I get the 'Cannot Verify Server Identity' for 'asolidreputa.biz'

1. Is this your corporate iPhone? Then please contact the system administrator of your corporate
2. If it is your personal device, in that case, do you have any profile installed by your corporate/organisation/enterprise/School Management?
   1. Erase the profile added by you If you have installed a profile on your own --> Install or remove configuration profiles on iPhone - Apple ...
   2. Or please contact the system administrator of the organisation who provided the profile to you
3. If you want to turn on SSL trust for that certificate, go to Settings > General > About > Certificate Trust Settings. Under "Enable full trust for root certificates," turn on trust for the certificate. Apple recommends deploying certificates via Apple Configurator or Mobile Device Management (MDM). --> Trust manually installed certificate profiles in iOS and iPadOS ...

Your may have a subscribed Calendar or a CalDAV or a CardDAV/LDAP account for Contacts or Calendars.

What happens when you click the "Details" on the error popup message (See the Pic below)

The best would be to Delete and Add the email account that is creating the issue.

You may also try changing SSL settings

Settings > Password & Accounts > [Select the Mail account} > [Tape on Account with the email ID} > Advanced > SSL Settings > [Disable]

Click <Account (in Blue)

Click on DONE (in Blue) when exiting in the previous screen

Probably you may have accepted an offer or subscribed for a spam Calendar accidentally. Watch the GIF below to know how to unsubscribe from these calendars. Look for an unknown Calendar on the device under subscribed calendars.

The pic below is self-explanatory if you have subscribed to a calendar.

I get the 'Cannot Verify Server Identity' for 'asolidreputa.biz'