Whitwell’s article this morning states that he is on over 200k a week which is understandable considering the type of transfer. Not sure where this 350k figure came from.
United salaries are x (basic including image rights) + y (Champions League) + z (appearance bonuses)
Instead of quoting a range, people either go for the minimum or the maximum. So in Sancho's case, those numbers might be x = 200K per week, y = 67K per week, z = 40K per start + bonuses of 500K after 20 and 40 starts (I'm using Memphis Depay's leaked contract as the template, his numbers were 75, 25, 20 and 250)
We aren't in the Champions League this season so all United players will be missing out on that element of their salary.
As well as Memphis' contract being leaked, Football Leaks also had details of Zlatan's, Pogba's and Sanchez's. A maximum figure in the £15m per year to £20m per year range would not be remotely surprising.
The season that Ronaldo, Varane and Sancho joined, while Dan James was the only significant departure, United's wages increased by £60m. Obviously there were other changes, different players out on loan, probably some new contracts, perhaps hired some additional coaches, sports science or other staff. Ronaldo was rumoured to be on £25m max so Varane and Sancho probably earned over £30m between them.