In the database, dpt_time and arr_time fields are varchar fields.
The created_at, updated_at, deleted_at fields are timestamps.
I help manage a VA who has all their dpt_time and arr_time set in the DB as local to the dpt/arr airport.
Those local times do not get changed to UTC anywhere or by anything.
That VA has been updated numerous times and is currently on the latest release version. Never once have those two fields changeed.
Timestamp will usually be in UTC or local time of the actual server location, depending on settings.
Varchar stores a short to medium string of characters.
Personally, I think having dpt/arr in local time (especially across multiple timezones only makes it more confusing for users. Doing everything in one time 'zone' (UTC) is much simpler.
In the real world, if you were to ask ATC for a time check you would receive the time in UTC.