The former SPG Amex card (now Bonvoy Amex vanilla) earns 2 Marriott Bonvoy points per dollar spend. It was 1 SPG point up until August x, the date of the end of the SPG program. Those old points were transferrable into Bonvoy points at a 1:3 ratio.
So yes, the SPG Amex earning rate was devalued by 33%