The sanitize of the save method and the convert to method interfere with each other

The format required by the block `save` method:
```javascript
static get sanitize(){
return {
url: false,
caption: {
a: true
}
}
}
```
The outermost object returned is a property, not a label.
`convent to` also uses this method, but it passes the result directly as a rule to and HTMLJanitor, as shown in the following figure



which causes the cleanup to fail.
Also, I noticed that even with the sanitize method configured, the `save` method still didn't clean up the data.