Can't merge the stack: either stuck while merging via GitHub UI, or getting false-negative error via CLI

See the stack up to https://github.com/react/react/pull/37498. All PRs were approved.

When I've attempted to merge it via UI, the merging was just stuck and never finished.
When attempted to merge via CLI, always received this error:
```
gh stack merge 37498 --yes --squash

Merging #37503, #37500, #37498 into main via squash...
✗ merge failed: protected branch 'main' check failed:
Waiting on 1 reapproval from someone other than the last pusher. Review from eps1lon is stale because it was submitted before the merge base changed.
Stack merges are atomic, so nothing was merged
```

This is incorrect, because merge based didn't change after the approval.

I was able to merge the bottom PR of the stack, but this extremely painful, because after that the base actually changes, and now I need to get re-approval from the reviewers. Please, could you finally fix the stacks?

使用 issue 中描述的 stack 和核准狀態，透過 `gh stack merge 37498 --yes --squash` 重現，然後追蹤 merge 命令的受保護分支檢查。沒有指定檔案或測試；完成表示當 merge base 未變更時，CLI 和 GitHub UI 不再阻擋此 stack，同時仍遵守真正的重新核准要求。

由索引模型根據 Issue 內容生成。