I have a problem please help me

Please see the Apple support links below. This should get rid of the rogue calendar/profile.

Delete spam calendars and events on iPhone - Apple Support

How to remove calendar spam on your iPhone — Apple Support

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 ...

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

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

If you are referring to this article where they are referring to iOS 16 --> List of available trusted root certificates in iOS 16, iPadOS 16, macOS 13, tvOS 16, and watchOS 9 - Apple Support (IN)

iOS 16, 16.3, 16.5/16.6 have different Store Versions and Asset Versions. Please go through my entire post

For iOS 15.7.8 and iOS 16.6 refer to the pic below

This is the trust store version for iOS 16.5 - 2023032800. Please see the pic below on iOS 16.5 iPhone 12 Pro.

Learn about Available trusted root certificates for Apple operating systems - Apple Support

This is part of iOS updates which can be clearly seen below

All my devices, iPhone 8 (iOS 16.0), iPhone 12 Pro (iOS 16.1.1) & iPhone 13 Pro on iOS 16.1.1 also iPad Pro on iPadOS 16.1 are with Trust Store Version: 2022070700 and Trust Asset Version 18

iPhone SE (1st Gen) iOS 15.7 2022031500 and Trust Asset Version 18

Earlier, iPhone 8, SE (1st Gen), iPhone 12 Pro & iPhone 13 Pro on iOS 15.6.1 also iPad Pro on iPadOS 15.6.1 all are with Trust Store Version: 2022031500 and Trust Asset Version 17

iPhone 6 iOS 12.5.5 Trust Store Version 2018121000, Does not have Trust Asset Version

After updating my iPhone 6 to iOS 12.5.6 it still has Trust Store Version 2018121000, Does not have Trust Asset Version

There is an old discussion thread on Trust Asset Versions that may help you understand --> Trust asset version 11. - Apple Community

Please check the iOS versions on each device again

Learn about Available trusted root certificates for Apple operating systems - Apple Support

This is part of iOS updates which can be clearly seen below

iPhone 12 Pro iOS 16.3 Trust Store Version: 2022070700 and Trust Asset Version 20

iPhone 8 iOS 16.2 Trust Store Version: 2022070700 and Trust Asset Version 20

iPad Pro 9.7" iOS 16.2 Trust Store Version: 2022070700 and Trust Asset Version 20

iPhone 13 Pro iOS 16.2 Trust Store Version: 2022070700 and Trust Asset Version 20

I may have missed Asset Version 19

All my devices, iPhone 8 (iOS 16.0), iPhone 12 Pro (iOS 16.1.1) & iPhone 13 Pro on iOS 16.1.1 also iPad Pro on iPadOS 16.1 are with Trust Store Version: 2022070700 and Trust Asset Version 18

iPhone SE (1st Gen) iOS 15.7 2022031500 and Trust Asset Version 18

Earlier, iPhone 8, SE (1st Gen), iPhone 12 Pro & iPhone 13 Pro on iOS 15.6.1 also iPad Pro on iPadOS 15.6.1 all are with Trust Store Version: 2022031500 and Trust Asset Version 17

iPhone 6 iOS 12.5.5 Trust Store Version 2018121000, Does not have Trust Asset Version

After updated my iPhone 6 to iOS 12.5.6 it still has Trust Store Version 2018121000, Does not have Trust Asset Version

There is an old discussion thread on Trust Asset Versions that may help you understand --> Trust asset version 11. - Apple Community