https://www.postgresql.org/docs/current/datatype-datetime.html
https://www.postgresql.org/docs/current/functions-datetime.html
https://www.postgresql.org/docs/current/functions-formatting.html

... field_date >= now() - '30 days'::interval ...

field_date: timestamp without time zone

using ... at time zone 'UTC'
https://postgrespro.ru/docs/postgrespro/17/functions-datetime#FUNCTIONS-DATETIME-ZONECONVERT

2023
https://habr.com/ru/articles/772954/