Applying a [numbered / bulleted] list to multiple lines works differently in each mode

[Justin-MSE]

Describe the bug

Markdown mode:

• After selecting and applying a numbered list, the numbers assigned to each line are the same. Switching to rich text [and back to Markdown] fixes the numbering. This is not a bug, as Marijn notes in a comment on MSE, but it would be nice to have it apply the proper numbering in the first go itself (like in the Github editor).
• Compared to rich text mode (and the old editor), the numbering is applied to all the lines. In the case of bulleted lists, the bullet points are also applied to all the lines in Markdown mode.
• In the case of double line breaks, the [numbers / bullet points] are applied to blank spaces as well (as shown in the GIF below).

Rich text mode:

• After selecting all the lines, with either single or double line breaks, and applying a numbered list in rich text mode, the numbering is only applied to the first item in the list, as is the case in the old editor. This is also the case with bulleted lists.

To Reproduce
Steps to reproduce the behavior:

1. Type text on multiple lines with single line breaks.
2. Select all lines.
3. Apply [Numbered / Bulleted] list to the selected text in Markdown mode.
4. Repeat using double line breaks.
5. Repeat the above in rich text mode.
6. Observe the difference.

Expected behavior
Make the way numbering is applied consistent in both modes.

Screenshots

1. Single line break applied:

   

2. Double line break applied:

   

3. Comparison with the old editor:

Desktop (please complete the following information):

• OS: Windows 11
• Browser: Chrome
• Version: 104.0.5112.101

Additional context
Also on MSE: https://meta.stackexchange.com/a/380604/513150