[Bug] insideBottomLeft label position not work with rich fontSize

### Version

5.3.3

### Link to Minimal Reproduction

https://codesandbox.io/s/disk-usage-forked-qc81o3?file=/index.js:879-895

### Steps to Reproduce

1. see the codesandbox index.js
2. notice the label position is "insideBottomLeft"
3. see it is using the rich.a for the first line of the label
4. notice rich.a has the fontSize of 18

### Current Behavior

Label is displayed in top left

### Expected Behavior

I asked label to please display in bottom left and she went to the top left instead

### Environment

```markdown
independent of environment: see codesandbox
```

### Any additional comments?

try to delete the rich and notice the label went to the right spot