The store size of TiFlash unexpectedly increases with update sql

[flowbehappy]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

Run workloads with only update sql in format_version = 3. And then change to 4.

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

The size of tiflash is not changed.

3. What did you see instead (Required)

• A: change format_version = 4
• B: run alter table xxx compact tiflash replica

4. What is your TiFlash version? (Required)

v6.1.0 nightly, fff77b4