Unrecognized Node Type Warning

We are using PostgreSQL 12.13. We are noticing that queries that attempt to retrieve an element of an array by specifying its position cause a warning to be emitted: "WARNING: unrecognized node type: 110".

Would appreciate your help diagnosing the issue and identifying steps to resolve.

Queries that reproduce the issue:

SELECT ('{0}'::int2[])[0];
WARNING: unrecognized node type: 110
int2
------

(1 row)

SELECT ('0'::int2vector)[0];
WARNING: unrecognized node type: 110
int2vector
------------
0
(1 row)

SELECT (indkey::int2[])[0] FROM pg_index limit 1;
WARNING: unrecognized node type: 110
indkey
--------
1
(1 row)

SELECT scores[1], scores[2], scores[3], scores[4] FROM (select('{10,12,14,16}'::int[]) AS scores) AS round;
WARNING: unrecognized node type: 110
WARNING: unrecognized node type: 110
WARNING: unrecognized node type: 110
WARNING: unrecognized node type: 110
scores | scores | scores | scores
--------+--------+--------+--------
10 | 12 | 14 | 16
(1 row)

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