UPDATE 2020-11-27 16:55 IST: We've updated the article with 8T-specific survey as well
OnePlus routinely asks for feedback regarding new updates, and now it's made an OxygenOS 11 survey for 8T devices. It previously made a similar survey for 8-series devices as well. There are a total of 16 questions mostly asking for your opinion on new design/features. They're accompanied by pictures to help you better understand each question, so even if you don't have an 8-series (or an 8T) device you can still throw in your 2 cents.
Given how OOS11's design has been controversial (it can be seen as a clone of Samsung's OneUI), this survey might be a good chance to try and get OnePlus to change some design decisions (or keep them, depending on whatever you like the new design or not).