Time zone offset being subtracted from utc timestamp when inserting into column while using prepared statements

[skunkworker]

rails 6.1.4.1
activerecord-jdbcpostgresql-adapter (61.1-java)
activerecord-jdbc-adapter (61.1-java)
jdbc-postgres (42.2.14)

jruby 9.2.19.0 on openjdk8

application.rb

config.time_zone = "UTC"

Table "public.foobars"
 Column            |            Type             | Collation | Nullable |                     Default
--------------------------------------------------------+-----------------------------+-----------+----------+--------------------------------------------------
 id                | integer                     |           | not null | nextval('foobars_id_seq'::regclass)
 created_at        | timestamp without time zone |           |          |
 updated_at        | timestamp without time zone |           |          | 

When prepared statements are turned on and a record is inserted into the database, the active record debug log shows the correct UTC timestamp with an offset of +00:00.

[DEBUG] [2021-10-08 13:13:20 -0600] Foobar Create (31.2ms)  INSERT INTO "foobars" ("created_at", "updated_at") VALUES (?, ?)  [["created_at", Fri, 08 Oct 2021 19:13:20.573182000 UTC +00:00], ["updated_at", Fri, 08 Oct 2021 19:13:20.573363000 UTC +00:00], ]

However the inserted record takes my current offset (MDT -6:00) and applies it to the record, saving the incorrect time.

app_development=# select * from foobars;
-[ RECORD 1 ]------------------------------------------+-----------------------------------------

created_at                                             | 2021-10-08 13:13:14.411114
updated_at                                             | 2021-10-08 13:13:14.411256

Turning off prepared statements solves this problem.

[skunkworker]

Looking into this more, the current timezone in my postgres instance is America/Denver. But once again, MRI does not have this issue using the pg adapter but JRuby does.

psql (13.4)
Type "help" for help.

testdb=# show timezone;
    TimeZone
----------------
 America/Denver
(1 row)

[skunkworker]

I suspect this isn't a commonly run into issue, because most if not all production databases would be running on a host in UTC time and postgres set to UTC.

[akimd]

Maybe not common, but does happen. We have been hit. It results in a big mess :(