Wrong order of neo fields when using richtext (ckeditor) with nested entries

[Jones-S]

Bug Description

We use Neo fields to create a Page Builder where editors can put together different content blocks. We do this for years now but recently we detected a very weird behaviour: When adding a new Richtext Block (ckeditor) and if we nest an entry (Button) inside, this blocks is now returned as the first item of the array instead of the last.

To better understand I have created this short screen recording:
https://www.dropbox.com/scl/fi/yl81jao9u9g175q6chakx/Craft-Richtex.mov?rlkey=ge0b87tvpb4q552e0gjbewcw0&e=1&st=v72wkzpg&dl=0

I first escalated this to the Craft team and they pointed me to neo. They were also able to reproduce.

This is at the moment kind of a critical bug for us and for one of our clients, as they can't really fill in the content, if the position is always changing and not corresponding to what the editor says.

Thank you in advance.

Steps to reproduce

Please contact me via PM and I am glad to share you a zip file with a DB dump, composer json and the templates for reproduction.

Expected behaviour

The new neo block should be at the end corresponding to the content editors position.

Neo version

5.2.21

Craft CMS version

Craft Pro 5.5.7

What is the affected Neo field's propagation method?

No response

Does this issue involve templating, and if so, is eager-loading used?

This is not a templating issue