Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

1. Deploy a tidb cluster with tiflash, using 32c256G machine for tiflash instance
2. Run br restore for a large dataset
3. After the "download sst stage" is finished, tiflash enter the "ingest sst stage", upgrade the cluster version to v8.5.4 including tiflash

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

tiflash should use 32 concurrency at max for ingest sst after upgraded to v8.5.4

3. What did you see instead (Required)

tiflash only use 16 concurrency at max for ingest sst after upgraded to v8.5.4

4. What is your TiFlash version? (Required)

v8.5.4