United Airlines MileagePlus In 2018 launched a promo called Mile Play trying to get members to spend and fly more. They have had these offers every few months and just launch a new one for June.
The Mile Play promotion is tailored to each select member based on his/her recent activity with United. It may require buying more business class tickets or flying a certain number of trips through August 4, 2019.
You can try your luck registering for this offer here.
United Airlines has run similar offers for years under different name and launched these “Mile Play” promos in early 2018.
My account was not eligible for this (never has been) because I moved it to outside of North America few years ago.