Regression in INSERT ... SELECT query introduced in release-8.0

[GuptaManan100]

Overview of the Issue

Consider the following query -

INSERT INTO main.user_privacy_consents (user_id, accepted_at)  SELECT user_id, accepted_at FROM (SELECT 1 as user_id, 1629194864 as accepted_at) AS tmp WHERE NOT EXISTS (SELECT user_id FROM main.user_privacy_consents WHERE user_id = 1)

This query produces the following plan in release-7.0 via V3

{
  "QueryType": "INSERT",
  "Original": "INSERT INTO main.user_privacy_consents (user_id, accepted_at)  SELECT user_id, accepted_at FROM (SELECT 1 as user_id, 1629194864 as accepted_at) AS tmp WHERE NOT EXISTS (SELECT user_id FROM main.user_privacy_consents WHERE user_id = 1)",
  "Instructions": {
    "OperatorType": "Insert",
    "Variant": "Unsharded",
    "Keyspace": {
      "Name": "main",
      "Sharded": false
    },
    "TargetTabletType": "MASTER",
    "MultiShardAutocommit": false,
    "Query": "insert into user_privacy_consents(user_id, accepted_at) select user_id, accepted_at from (select 1 as user_id, 1629194864 as accepted_at from dual) as tmp where not exists (select user_id from user_privacy_consents where user_id = 1)",
    "TableName": "user_privacy_consents"
  }
}

However, in release-8.0, the following error is seen -

unsupported: sharded subquery in insert values

Reproduction Steps

Steps to reproduce this issue, example:

1. Copy the given query in one_case.txt and run TestOne from plan_test.go

Binary version

Regression introduced in release-8.0