The current markdown field, at least in my instance, is reduced to half (of the already reduced limit of the general composer).
Unfortunately, in practice it is almost unusable. The composer buttons are not visible, its placeholder barely manages to show 20 words and no more. I hope it improves soon, it’s a great feature to allow 
[EDIT] I think it would also be very valuable to enable image uploads in the text field, for use in wiki or guide creations, where they need to be ordered and not displayed at the end of the topics created.