Let's not forget that Oracle DB uses the system timezone as the datatype storage (not sure what other database do to be honest) so unless you were running your DB machine as UTC by default their timestamp storage would be ambiguous for DST shift and that's their default. Why wouldn't they store everything in UTC and use the system timezone for parse/formatting I have no clue.
I've been pushing to run ALL servers as UTC for a few decades now... always store/transmit date+time as UTC as well. If it's mapped to a locale, pair it with that locale... let the client translate to/from local.
