Items in data like your tickets are made into observable objects. This is to allow reactivity (automatically re-rendering the UI and other features). This is expected and the returned object should behave just like the array.
Check out the reactivity docs because you need to interact with arrays in a specific pattern or it will not update on the ui: https://v3.vuejs.org/guide/reactivity-fundamentals.html
If you do not want to have reactivity – maybe you never update tickets on the client and just want to display them – you can use Object.freeze() on response.data;