Editor has problems with plenty long multi-level lists

[ericfischereu]

Describe the bug
If you have long markdown documents with a lot of quite long lists and headings in between, it can happen that list indention does not work properly. So instead of ending the list/changing to a normal text block after a double enter it creates endless list items. Additionally, a SHIFT+TAB, which should reduce the list indention does nothing.

The affected documents mix a lot of things, especially headings, lists and items/links from the smart picker. A reload of the editor usually fixes the issue.

To Reproduce
Steps to reproduce the behavior:

1. create a long markdown document with different sections/levels of headings, long unordered lists with different indention levels, and items from the smart picker (Deck cards e.g.)
2. try to change the indention of list items via TAB, SHIFT+TAB or double ENTER

I wasn't able to figure out if this always happens at a certain point, but it happens regularly.

Expected behavior
Since the file format is not broken, the editor should always work the same in regards of lists

Screenshots

Server details:

• Nextcloud version: 34.0.4
• PHP Version: AIO :20260916_075031
• Database: Postgres AIO :20260916_075031

Client details:

• OS: Linux Mint
• Browser: Zen & Firefox
• Browser version: 1.22.2b (Firefox 156.0) (64-Bit)
• Device: Lenovo Thinkpad X1 Yoga G6

Logs

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