No way to make a write-in report for a sentence
After every sentence, whether you were correct or made an error, you can give a report. On the old website, you could have left a custom write-in report if none of the provided options accurately described your problem. Today I've noticed that the option is missing:
(This is the "error" message I was given: https://imgur.com/98ZwzZT. I got a different selection of options for a red error, no write-in either.)
Is there a reason for getting rid of the write-in reports, or is it just an oversight?
Duolingo are aware this is missing at the moment. They have listed this as a feature that is
Ability to write a custom report for a sentence
I cannot provide a full answer to the question of whether there is a reason for this or just an oversight.