Issue: logging.basicConfig(level=logging.ERROR) unexpectedly changes log format of custom logger

# Bug report

### Bug description:

## Issue: `logging.basicConfig(level=logging.ERROR)` unexpectedly changes log format of custom logger

**Environment**  
- Python version: 3.11  
- OS: Linux / Alibaba Cloud WebIDE (also reproducible locally)

**Steps to Reproduce**  
Run the following code:
```python
import logging
loger = logging.getLogger(__name__)
loger.error('start1')
logging.basicConfig(level=logging.ERROR)
loger.error('start1')
```

**Actual Output**
```
start1
ERROR:__main__:start1
```

**Expected Output**  
According to Python `logging` documentation, `basicConfig` should not change the output format when only `level` is specified (no `format` parameter). The format of both log lines should be identical (e.g., both `ERROR:__main__:start1`).

**Description**  
- The first `loger.error('start1')` prints only the message `start1`, missing log level and logger name.
- The second call (after `basicConfig(level=logging.ERROR)`) prints the normal format `ERROR:__main__:start1`.
- `basicConfig` only set the `level` parameter without specifying `format`, yet it altered the output format for the custom logger.

**Additional Notes**  
- The issue is reproducible both in Alibaba Cloud WebIDE and local environment.
- Direct calls like `logging.error('start2')` always print the normal format and are unaffected.

---

## 问题报告：`logging.basicConfig(level=logging.ERROR)` 意外改变自定义 logger 的日志格式

**环境**  
- Python 版本：3.11  
- 操作系统：Linux / 阿里云 WebIDE（本地同样复现）

**重现步骤**  
运行以下代码：
```python
import logging
loger = logging.getLogger(__name__)
loger.error('start1')
logging.basicConfig(level=logging.ERROR)
loger.error('start1')
```

**实际输出**
```
start1
ERROR:__main__:start1
```

**期望输出**  
根据 Python `logging` 文档，当只指定 `level` 参数（未指定 `format`）时，`basicConfig` 不应改变输出格式。期望两次输出的格式一致（例如均为 `ERROR:__main__:start1`）。

**问题描述**  
- 第一次 `loger.error('start1')` 仅输出消息内容 `start1`，缺少日志级别和 logger 名称。
- 第二次调用（在 `basicConfig(level=logging.ERROR)` 之后）输出正常格式 `ERROR:__main__:start1`。
- `basicConfig` 仅设置了 `level` 参数，未设置 `format`，但却改变了自定义 logger 的输出格式。

**补充说明**  
- 该现象在阿里云 WebIDE 和本地环境均可稳定复现。
- 直接调用 `logging.error('start2')` 始终输出正常格式，不受上述影响。

### CPython versions tested on:

3.11, 3.13

### Operating systems tested on:

Linux, Windows

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Issue: logging.basicConfig(level=logging.ERROR) unexpectedly changes log format of custom logger #151121

Bug report

Bug description: