After testing, if the categories that have been applied to the event are changed, the categories on the event are also changed.
For example, if the color of a category is changed, the color applied to that category is updated on all events.
If a category is deleted, that category disappears on all events.
Hope this helps.
If the reply is helpful, please click Accept Answer and kindly upvote it. If you have additional questions about this answer, please click Comment.