TiFlash throw false positive error when cast is executed in non-readonly statement

[windtalker]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

Before execute the example, should set global tidb_enable_tiflash_read_for_write_stmt=on; in TiDB

create table t1(id int, amt decimal(21,3));
create table t2(id int, sumamt decimal(21,3));
insert into t1 values(1,100.333),(1,200),(2,100),(2,200);
alter table t1 set tiflash replica 1;

insert into t2
select /*+ read_from_storage(tiflash[t1]) */
id,cast(sum(amt)/9 as decimal(21,3))
from t1
group by 1;

It throw errors like this

ERROR 1105 (HY000): other error for mpp stream: From MPP<query:<query_ts:1682298546286311977, local_query_id:2, server_id:3778413, start_ts:441004470109995009>,task_id:2>: Code: 0, e.displayText() = DB::
TiFlashException: Truncate error cast decimal as decimal, e.what() = DB::TiFlashException,

But if read from TiKV, the insert success.

2. What did you expect to see? (Required)

3. What did you see instead (Required)

4. What is your TiFlash version? (Required)

TiDB v6.5.1