I would replace it with unfaced insulation and then cover it with poly sheeting or similar.

Thanks for the reply and suggestion. I'd prefer not to cover w/ sheeting because I don't want to restrict access to plumbing and electrical. I also don't want to go crazy with this effort. The plumbing and HVAC are all below the joists so that would be complicated. Would you still recommend replacing the insulation by itself?

Is the basement heated/ conditioned space? What general geographic area do you live?

ETA, without knowing the details of what the basement space is used for, the PO's may have installed the insulation to reduce noise transfer between levels.

Thanks for the reply. The basement is unfinished and not conditioned (no heat or AC ducts open to the basement). The only conditioning item I currently have is a dehumidifer that is set to 55% and drains into the sump pit. It does a decent job of regulating the humidity however it just doesn't move the air enough to feel fresh.

Im thinking about getting an air purifier for the basement and running that regularly. Maybe see how that works before I go replacing insulation. My concern with the insulation is just that it may be a living-space for mold and mildew and I'm not sure if replacing or removing would help with that cause. Maybe the air purifier and improved dehumification would do accomplish 90% of what I'm after.

The insulation is pointless. Dehumidify and keep any basement windows closed year-round.

Unless the basement is sealed tightly, it is part of your conditioned space whether or not there are HVAC ducts. If the furnace is in the basement and it is not a sealed combustion unit, it is getting combustion air from the basement.