Rails casts timestamptz to UTC in Postgres - ruby-on-rails

Question

I'm on Rails 7.0.4 and Postgres 15. I have a trigger that checks if a timestamp(6) with time zone is within a certain date range:
CREATE TABLE public.contracts (
id bigint NOT NULL,
starts_on date NOT NULL,
ends_on date
);
CREATE TABLE public.time_entries (
id bigint NOT NULL,
contract_id bigint,
"from" timestamp(6) with time zone,
"to" timestamp(6) with time zone
);
And this is the trigger:
CREATE FUNCTION time_entries_contract_trigger() RETURNS trigger AS $time_entries_contract_trigger$
BEGIN
IF EXISTS (SELECT 1 FROM contracts WHERE contracts.id = NEW."contract_id" AND NEW."from"::date < starts_on) THEN
RAISE EXCEPTION 'from % is before contracts.starts_on', NEW."from";
END IF;
IF EXISTS (SELECT 1 FROM contracts WHERE contracts.id = NEW."contract_id" AND NEW."to"::date > ends_on) THEN
RAISE EXCEPTION 'to % is after contracts.ends_on', NEW."to";
END IF;
RETURN NEW;
END;
$time_entries_contract_trigger$ LANGUAGE plpgsql;
CREATE TRIGGER time_entries_contract_trigger BEFORE INSERT OR UPDATE ON time_entries
FOR EACH ROW EXECUTE PROCEDURE time_entries_contract_trigger();
And I set the default timezone like this:
module App
class Application < Rails::Application
# ...
config.time_zone = "Europe/Berlin"
# ...
end
The problem now is, that whenever I try to store a TimeEntry, Rails converts it to UTC and I get an error like this:
> contract = Contract.create(:contract, starts_on: Date.parse("2021-12-19"))
> contract.time_entries << build(:time_entry, from: Time.zone.parse("2021-12-19T00:00"))
ActiveRecord::StatementInvalid:
PG::RaiseException: ERROR: from 2021-12-18 23:00:00+00 is before contracts.starts_on
CONTEXT: PL/pgSQL function time_entries_contract_trigger() line 4 at RAISE
It makes sense insofar, that Rails converts Time.zone.parse("2021-12-19T00:00") to UTC and my trigger just casts it to a date with NEW."from"::date, just returning the date part (which now is 2021-12-18 and not 2021-12-19).
My questions now are:
How could I force Rails to store the columns with the timezone information in it? My Postgres columns are already timezone aware, so I guess converting it to UTC doesn't make sense any more? Or are there any drawbacks that I'm missing?