Yes, used different messages max sizes, with 2000 characters got the best speed but got the account banned, using 20000 is a great middle term and not banned for now, could get banned anyway, its an educational project
During the Facebook outage of a few years ago, WhatsApp messages still worked but I couldn't send an image. I think images are uploaded to Facebook-related servers and messages are through a separate real-time infrastructure, and it's likely that the message includes the fuzzy thumbnail and a url for the image from the other server.
I was on a boat recently where WhatsApp was free to use, and you had to pay to use the rest of the internet. You could send and receive messages but attempting to send an image, which wasn’t even all that big in size, did not work on the free connection.
It must be either message size, or WhatsApp using a separate host name for attachments.
Using less characters got you banned? I don't understand why that would happen. I would think using more characters would be more likely to get you banned since it's less like what normal users do.
Well increasing the usage would also increase the number of messages.
How does Whatsapp choose to ban people? Total messages sent? Then increasing the message size doesn't stop you from being banned, it just makes it take longer before you're banned. Messages/second? Then avoiding the ban by a message size restriction seems like a very clumsy way of doing it; it would be much more straightforward to avoid the ban by limiting the messages/second.