INTERVAL MINUTE TO SECOND didn't do what I thought it would do

PG 14.13

The goal of "(now() - query_start)::INTERVAL MINUTE TO SECOND" column is to
see how many minutes and seconds ago that the query started. (Why?
Because that's useful to me, and the people I show the output to when
queries run for more than a few minutes. We don't need to see hours and
days; just the total MMMMM:SS.mmm.)

I'd hoped that ::INTERVAL MINUTE TO SECOND would do the trick, but MINUTE
TO SECOND seems to be ignored.

Is there cast magic that does what I want?

TAPc=# select pid
,datname as db, usename
,to_char(query_start, 'YYYY-MM-DD HH24:MI:SS.MS') as qry_start
,(now() - query_start)::INTERVAL MINUTE TO SECOND as qry_elapsed
,cast(state as char(11)) as state
from pg_stat_activity
WHERE pid != pg_backend_pid()
and state != 'idle';
pid | db | usename | qry_start | qry_elapsed
| state
---------+------+------------+-------------------------+-------------------------+-------------
657996 | | replicator | 2024-11-11 21:03:00.992 | 57 days
16:38:22.342449 | active
4070070 | TAPc | TAP | 2025-01-08 13:41:23.202 | 00:00:00.132817
| active
4070069 | TAPc | TAP | 2025-01-08 13:41:23.140 | 00:00:00.194222
| active
4070065 | TAPc | TAP | 2025-01-08 13:41:23.238 | 00:00:00.096418
| active
(4 rows)

--
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