Experiencing the same with my 2.0L MK7 TDI at 39,200 miles.
Earlier this week my Check Engine Light and AdBlue refill warning light (600 mi) came on. Checked under the hood and found the crystallization buildup(pic below). Ran my OBDII Reader which displayed a P20E8 error code - "Reductant Pressure too Low."
Odometer is at 39,200 so about 3K Miles out of warranty. Took into dealer and they diagnosed as a crack in dpf seal. Parts are coming in Monday. They say they should have no problem getting this covered since I'm so close to warranty expiration and that they have tech notes of this happening on similar models.
I'll save fighting words for later if they deny coverage. Planning on doing buyback at some point next year, but a pricey fix could move up that date if there are bigger problems and they refuse to cover.