The fix for this issue is now available in the latest update 14.0.2 of InDesign 2019.
If you are unable to see the update notification yet, open the menu (three dots) from the top-right of Creative Cloud desktop application and click on ‘Check For App Updates’.
Once the update button is shown against InDesign, click on the button to update to Id 14.0.2.
If you face any problems with the new update, do let us know in the comments.
I definitely would like to see this fixed in the next release or even a patch if possible.
This happens with both IDML and ICML export. Potentially a scripting event can be a workaround so that before export, the 8000th character is checked and if it is a paragraph return a blank space is added before it.