The screenshot should explain the issue perfectly - but in short:
After I created a bulletpoint list, the next headline I tried to create is formatted incorrectly. However, in the preview it is correct displayed as headline - only in the markdown editor not.
This issue does not occur for me. Maybe you can also share the Markdown that is visible on the screenshot as text, then I would also test it with that.
Could it be due to an unusual combination of whitespaces or something similar?