Variant Type GROUP BY NOT_IMPLEMENTED Error

[BooBSD]

Describe the unexpected behaviour

It looks like GROUP BY doesn't work over Variant type.

How to reproduce

ClickHouse client version 24.2.1.628 (official build).
Connecting to database staging at example.com:9000 as user admin.
Connected to ClickHouse server version 24.1.2.

SET allow_experimental_variant_type = 1;

CREATE table test_variant
(
    event_name  LowCardinality(String)  CODEC(ZSTD),
    event_value Variant(String, UInt64) CODEC(ZSTD),
    created_at  DateTime64(3, 'UTC')    CODEC(DoubleDelta, ZSTD)
)
ENGINE = ReplacingMergeTree()
PARTITION BY toYYYYMM(created_at)
ORDER BY (event_name, created_at);

INSERT INTO test_variant VALUES ('test', NULL, now()), ('test', 'Test1', now() + 1), ('test', 42, now() + 2), ('test', 'Test2', now() + 3);

And final query:

SELECT
    event_name,
    argMax(event_value, created_at) AS last_value,
    max(created_at) AS last
FROM test_variant
FINAL
GROUP BY event_name

Query id: 7171774d-d76b-47f7-b121-b4d2b5782355


Elapsed: 0.131 sec. 

Received exception from server (version 24.1.2):
Code: 48. DB::Exception: Received from example.com:9000. DB::Exception: Cannot insert field Test2 to column Variant(String, UInt64): While executing ConvertingAggregatedToChunksTransform. (NOT_IMPLEMENTED)