Thanks for reaching out to the Zoom Developer Forum and welcome to our community! I am happy to help here!
I do not think there is other documentation available about this, other than the endpoint you mentioned.
But let me look into this internally and I will come back with an update shortly.
Sorry for the late reply
I heard back from our Engineering team about this issue. It looks like the behavior that you noticed was caused by a task we ran in one of our releases.
We have identified it and we will fix it this weekend, so the format will go back to <timestamp>\t<username>:\t<message> .