Funnel de conversion canonico de 6 pasos (ADR conversion-analytics).

tz (an IANA name) cuts the days at 00:00 of that zone instead of UTC, for every step and for activation.matures_at, and the answer then says so in timezone. Without it nothing changes: the same UTC days, the same queries with the same parameters, the same answer.

#62: a parameter it does not take is a 422 that names it (?days=30 used to answer the default 30-day funnel in silence), and the answer states the window it computed in window (from/to inclusive days, and the time zone they are cut in).