Wrong primary category assigned when multiple categories are selected

When a user adds an event to the calendar and selects multiple categories, the primary category is automatically set to the first category in the overall category list, not the first category selected by the user.

The primary category can be manually changed from the dropdown to one of the selected categories. However, the issue is that this first category in the list should not appear at all unless it has been explicitly selected by the user.

Because the first category is assigned automatically, it often remains selected unintentionally. Many users overlook this, resulting in events being saved with an incorrect primary category.

Ideally, the primary category should only be one of the categories the user has actively selected. Alternatively, no primary category should be selected by default, and the user should be required to explicitly choose a primary category before saving the event.