[Bug]: (CalDAV) Changes to Calendar Events do not reuse invitation link

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github OR Nextcloud Community Forum (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

When updating a calendar event with attendees the changes generate a new invitation link instead of reusing or replacing old link, causing multiple links in the database for the same event.

Steps to reproduce

1. Create event with attendees
2. Change above event date or time
3. Check calendar_invitations table for generated links

Expected behavior

Changing the event should reuse existing link or replace the link with new link by either updating the row or removing the old rows

Nextcloud Server version

master

Operating system

Debian/Ubuntu

PHP engine version

PHP 8.3

Web server

Nginx

Database engine version

MySQL

Is this bug present after an update or on a fresh install?

None

Are you using the Nextcloud Server Encryption module?

None

What user-backends are you using?

• Default user-backend (database)
• LDAP/ Active Directory
• SSO - SAML
• Other

Configuration report

No response

List of activated Apps

No response

Nextcloud Signing status

No response

Nextcloud Logs

No response

Additional info

No response

No source file or test is named. Start by reproducing the issue with a CalDAV event that has attendees, then inspect the calendar_invitations table after changing its date or time. Done means updating the event reuses or replaces the existing invitation row rather than leaving multiple links for the same event.