Two sequential <blockquote> elements getting merged

@cilefen Why for 11, it is critical issue in 10 right?

This is not critical as there is no stored data loss.

All merge requests must be against the development branch which is 11.x-dev.

Yes, it is not data loss, but it is breaking a normal working mechanism. No user can add two blockquote sequentially.
see below example how its breaking content editing experiance
I have added below text

Post save what i can see

This is simple example it is breaking in many cases.
Still, you don't think this is a critical issue?

No I do not and the Drupal community agrees → . "Major" is probably ok.

Are you able to reproduce this bug on the CKEditor 5 demos? If you can this is going to be an "upstream" issue.

I am unable to reproduce this bug in a new Drupal 10.3.1 install by adding an article and using the default "Basic HTML" text format. The markup I get is as follows:

<blockquote>
    <p>
        A blockquote
    </p>
</blockquote>
<blockquote>
    <p>
        Another blockquote
    </p>
</blockquote>

There must be additional steps to reproduce the bug.

Yes, this is an issue with our preprocessor function where we are altering the html, closing this for working as expcted