I’m assuming you disabled REBAR from your comment above. REBAR is supposed to optimize data transfers between your cpu and gpu and it is recommended to turn it on. If the sim is using more vram than what is physically present on your gpu I recommend that you turn on FSR3 and start with quality mode and step down from there until you safely keep under your vram limit.
MS/Asobo are saying the vram oveflow issue will be fixed in SU2 so we’ll see soon.