Victory Points suddenly disappeared?

[Dwuemka]

@Sunaj

She says she hasn’t done anything except change alliances 2 or 3 times and otherwise played normally.

This is exactly what caused the reduction in total VP. See patch notes for 7.5:

@Gems-of-War

If a player decides to leave their Alliance they will lose 25% of their Total VP (Weekly VP will not be affected), All their current Loyalty, and their current Alliance Rank.