bug(rich-text) Pasting text from one list into another inserts as sub-bullet

Describe the bug
Copying text from one list bullet to another inserts the pasted text as a new sub-bullet.

To Reproduce

1. in rich text mode, add list items
2. copy one of them, or even a fragment of one (not the entire text from the list item)
3. paste it into a different list item
4. observe that it pastes as a sublist item, on the next level

Expected behavior
List items are pasted in as text. Copying multiple list items and pasting them in should be equivalent to pasting in multiple lines of text (this is how it works in Google Docs). Pasting in one list item or a fragment of one list item should just add it as text to the spot where it is being pasted.

Screenshots

Desktop (please complete the following information):

• Windows Chrome 103
• MacOs Firefox

Additional context
MSE Post

Start in the rich text mode and reproduce the issue by copying a list item or fragment into another list item. Check the paste handling involved and compare single-item, fragment, and multiple-item pastes with the expected plain-text and multiple-line behavior. Done means pasted content no longer becomes an unintended sublist.