3.4.x has major breaking datetime and timestamp issues

Our cloud environment runs with db servers hosted for particular customers in THEIR local headquarter timezone (say MDT). The mid-tier is Java and runs in UTC. The webclient run's in the user's local time zone.

Prior to 3.4.x series of JDBC drivers everything worked for many years without issue. Changing from 3.3.3 driver to 3.4.x breaks datetime handling generally.

For example, with 3.3.3 SELECT NOW() yields the correct server time.
With 3.4.1 this returns UTC.

Further, if you try to correct this behavior with JDBC connection string parameter connectionTimeZone=SERVER I get the following error:

ERROR: Unknown zoneId MDT

It seems to me that whatever the default 3.4.x behavior is it should be compatible with prior versions and not introduce breaking changes.