I own an Alienware AW2518HF 240Hz monitor purchased on August 6, 2018. This monitor says that it supports up to 240Hz, which includes 120Hz at 1080p. However, the PS5 can only recognize 1080p at 60Hz. I have read in other places that this may have to do with FreeSync being enabled, but I am not sure if FreeSync is normally enabled by default if not plugged into a PC (i.e. if its hardware enabled or software). In any case, I think you need to put out a firmware update (if that is even possible for this model?)