Facet of light has an upkeep of two with the new patch but Hardening Persistence only gives you one stack for Facet of Light. I was in the sPvP lobby when I tested this, but it also occurred at least on the Colosseum map. I also check the toughness gain and it was only giving me 40 instead of 80 when I was in the lobby (I didn’t get to see if it occured during a match).
In PvE Facet of Light only uses one upkeep and works just fine with Hardening Persistence.