Look at the numbering on the first level of the list on
I think that is triggered by editing the message after submittal.
Example with one level:
Example with two levels:
Ah no, actually the problem already comes on first submit, without any editing. Note that the preview does not have this problem.
Example with three levels:
Interesting; thank you for pointing this out.
My understanding is that this is in some huge piece of code in a library, and while the source does exist, unwrapping it would not be the best use of the donations we have had so far. These have been very generous but a day of work would use up the whole remaining budget.
I am surprised that multi level lists (both numbered lists and bullet points) work at all.