Is it legal to take away a pay raise in Virginia?

An employee received an hourly pay raise and a week later they took the
raise away and the employee was back to the wage he was paid prior to
the raise.

When the employee received the raise he was moved to another position
with the company and then without notice was required to go back to the
previous position and when the paycheck was received the raise had been
taken away without any notice/warning!

Any info on this topic would be greatly appreciated. Thank you!