Firebird 4 just before beta 2 changed how it derived the base UTC time for a named zone, by always using 2020-01-01. To make sure values in Jaybird are consistent, it must also use 2020-01-01 when deriving the value of a java.time.OffsetTime. Do be aware that this means the derived offset value is as it applies at 2020-01-01, so for example '20:58:00 Europe/Amsterdam' will be '20:58:00+01:00', even if the value is derived on a date during summertime. Especially when using CURRENT_TIME, this may yield confusing results.
See also jdp-2020-06 OffsetTime derivation for named zone (https://github.com/FirebirdSQL/jaybird/blob/master/devdoc/jdp/jdp-2020-06-offsettime-derivation-for-named-zone.md