It's usecase dependent so it seems like the application should deal with this, at which point persisting in UTC is still a reasonable choice.
If you store this in UTC and the timezone changes, you end up converting to the wrong time.
So for future events you should store local time with a location you can map to a timezone.
But if you want to have precise date time far in the future you must not use UTC based milliseconds representations unless you want to check for necessary database migrations every time the time zone definitions change.
My point in mentioning the solstice is that while some events are at “2pm”, others are “when something happens”.
Sure, UTC is not suitable for conducting astronomy. It is suitable for working with human friendly times, since it is the foundation of timezones.