Multiple aggregations in select slow on postgres

I have a table with columns: id, antenna_id, latitude, longitude. There are two composite indexes on (antenna_id, latitude) and (antenna_id, longitude). When I do a max(latitude) for a specific antenna id(s), the speed is acceptable, but doing a min and max for both latitude and longitude at the same time is very slow.

SELECT version()

PostgreSQL 12.3 on x86_64-pc-linux-musl, compiled by gcc (Alpine 9.2.0) 9.2.0, 64-bit

Query

SELECT max(latitude) FROM packets WHERE antenna_id IN (1,2)

Explain

Finalize Aggregate  (cost=439588.11..439588.12 rows=1 width=32)   ->  Gather  (cost=439588.00..439588.11 rows=1 width=32)         Workers Planned: 1         ->  Partial Aggregate  (cost=438588.00..438588.01 rows=1 width=32)               ->  Parallel Index Only Scan using idx_packets_antenna_id_latitude on packets  (cost=0.57..430103.40 rows=3393839 width=7)                     Index Cond: (antenna_id = ANY ('{1,2}'::integer[])) JIT:   Functions: 5   Options: Inlining false, Optimization false, Expressions true, Deforming true 

Duration

[2021-03-06 12:14:38] 1 row retrieved starting from 1 in 4 s 438 ms (execution: 4 s 400 ms, fetching: 38 ms) [2021-03-06 12:14:51] 1 row retrieved starting from 1 in 2 s 590 ms (execution: 2 s 560 ms, fetching: 30 ms) 

The explain looks almost identical for max(longitude), min(latitude) and min(longitude) on their own. Speed is acceptable.

But when I combine the queries

SELECT max(latitude), max(longitude), min(latitude), min(longitude) FROM packets WHERE antenna_id IN (1,2)

Duration

[2021-03-06 09:28:30] 1 row retrieved starting from 1 in 5 m 35 s 907 ms (execution: 5 m 35 s 869 ms, fetching: 38 ms)

Explain

Finalize Aggregate  (cost=3677020.18..3677020.19 rows=1 width=128)   ->  Gather  (cost=3677020.06..3677020.17 rows=1 width=128)         Workers Planned: 1         ->  Partial Aggregate  (cost=3676020.06..3676020.07 rows=1 width=128)               ->  Parallel Seq Scan on packets  (cost=0.00..3642080.76 rows=3393930 width=14)                     Filter: (antenna_id = ANY ('{1,2}'::integer[])) JIT:   Functions: 7   Options: Inlining true, Optimization true, Expressions true, Deforming true 

Question

Why does the second query which does the min and max on the latitude and longitude field not use the indexes? And how can I rewrite the query so that it is faster?