LEVEL is not a subsidiary of Vueling. It is an IAG subsidiary that they don’t seem sure what to do with. It’s main purpose seems to be to punish the misdeeds of various IAG op-co’s. Until recently it didn’t have its own AOC, it now has two, Anisec and OpenSkies/LEVEL France. The Vienna A321s came from AirBerlin the AMS A320s from Vueling and the A330s from IB. Similarlry it has two booking engines, one Iberia, one Vueling. It all feels rushed and temporary.
I think LEVEL is being used to ‘punish’ Vueling for poor operational performance on one hand. On the other, the Vueling pilots union demanded that all pilots are based in Spain, hence the transfer of AMS based aircraft to Anisec.