I have a 2017 with less than 1000 miles with this clutch issue, I call it clutch chatter at really slow speed. Mine had a leaky clutch cylinder and they replaced the clutch and pressure plate. The problem is still there and they have a case open with Ford.
I have about 7200 miles on the car now and have had low speed clunking and other various drivetrain vibrations/sounds since day 1. I've tried changing the trans and diff fluid to BG, swapped to a dampened CF drive shaft, installed a new clutch, and a MGW shifter....all of these things have helped improve the driving experience, but still hasn't completely eliminated those horrible clunking and various metal on metal sounds.
At this point, I'm just chalking it up to the inherent design on the mt82 and torsen diff with the 3.73s. I'm more than likley going to do a tr6060 swap and be done with it since I plan on keeping the car forever.
The fact that Ford revised the mt82 for 2018 makes me think they know it has been a lackluster trans.
I've got it too. Had it since day one. Someone told me it was the throw out bearing. It's annoying and concerns me a little. Hopefully it's nothing to worry about.