If you use a calendar via an ics file or a URL subscription with an external service provider (e.g. Google, Apple or other cloud providers), the calendar data is transferred to the provider's servers.

This can lead to the following data protection risks:

• Data transmission to foreign countries: Depending on the provider and server location, the data may be transferred to countries that may not offer a level of data protection comparable to that in the EU.
• Third-party data access: Theoretically external service providers can access the transmitted calendar content.
• Non-transparent data processing: There is a risk that the data will be processed for analysis purposes or for other purposes that you are not interested in.
• Sharing information without control: If an ICS URL is known, it can be used by unauthorised third parties.  It is not password-protected by default.

Recommendation: Consider alternative solutions. Use data protection-friendly calendar services or set up an internal calendar system.