That’s not how the trick works.
If you PLAYED 23-11 you would level after 7 WE. Losing 14 WE.
Because the Loot tickets count as 21 WE, you use all 21 WE, get the XP & loot from 21 WE and then level.
Edit:
Clarification:
23-11 is 2,837 XP for 7 WE.
Using 3 loot tickets MDB used 21 WE, got 8,511 XP, and triple loot before leveling and refill.
Without loot tickets MDB would use 7 WE, waste 14+ WE, got 2,837 XP and single loot before leveling and refill.
This is how to do it without loot tickets: