Required not working after emptying the field

[1zerro1]

Version 8.5.2.

Bug description : Required wont raise if the field is empty, but previously had a value.

Reason why : After deleting all text, the value = '<p></p>'

To reproduce
Simply put a MudRichTextEditor in a form

<MudForm @ref="form">       
  <MudExRichTextEdit                              
  Height="300"                        
  EnableResize="false"
  Required="true"
  Immediate="true"
/>
[...]

Step 1 (checking requires work): Load the page, then validate the form (form.validate();) , field won’t be valid because the value = null.
step 2: write some text in the MudExRichTextEdit
step 3: erase all the text from MudExRichTextEdit
Step 4: validate the form.

Required does not triggers