You don't have to do or apply anything, this is normal behaviour on reactive and mobile apps.
As different users can be using your app in different timezones, by default all datetimes are in the user's timezone on the browser/device side, and are in the server's timezone on server / database side.
If your server is in UTC zone, then they are stored in UTC.
So yes it is a bit weird if you don't know about this, but ask yourself what problem you have with this for your use case, if the answer is none, then just leave this normal behaviour as is.
Dorine