Over 30 years ago, Exxon (the big US oil company) started to buy a small
company that had "invented" such an energy saver.   It was the same basic
idea:  reduce the voltage to reduce the "reactive" current.   A "chip"
monitored things so that the voltage would continually seek the optimum
point of minimum current.   The hype was the same:  it would make a giant
difference in energy consumption.   The reality to most EEs that if it
worked it might save "a little."

Anyway, Exxon was willing to buy the company.   The critics of Exxon claimed
that Exxon wasn't making an investment but was trying to keep energy saving
stuff off the market (like the 100 mpg carburetor!).    Obviously, the BIG
OIL critics got just as carried away as the managers at Exxon.

I think I have seen it on display at some hardware stores once or twice in
the years between then and now.

The "scam" part is the excessive claims.   The basic idea works but only
saves some I^2*R loses in slightly loaded induction motors.