Thanks for bringing this to our attention. We're going to do some testing to see if we can replicate your issue and get it resolved. Thanks for pointing this out and we hope to get this back in order ASAP!
One technical point might be relevant. If I fill in the form for posting to a topic not by typing all the characters directly into the form field but by pasting a multi-paragraph text I wrote offline with tabbed paragraph indents which I intend to delete before saving, the paste shows up with boxes and editing it is much harder. I think a programmer may be using a table feature and somehow that makes editing harder. I assume sending in a whole email reply to a topic works like pasting in a tab-indented multi-paragraph text.
Based on my experience with this field, it appears the form adds an extra line break that's invisible in the form but visible in a text file.
Thanks for testing.