1 to 2 psi pressure loss per month (for passenger car tires) is considered by the industry to be the upper limit of acceptable. I suspect this goes back to the first days of tubeless tires as this was in place when I first arrived, hasn’t changed in 50 years , and the vast majority of tires don’t experience anything even close.
I also suspect that this value is so high because tire dealers don’t want to have to deal with fixing it - for which they don’t get any revenue.
So I think a 1 to 2 psi pressure loss per month to be worthy of finding out where the seepage is occurring. A common culprit is corrosion of alloy wheels. But I would do this myself (instead of having a tire dealer do it) using a spray bottle of soapy water. Once the problem area has been found, then take it to a tire dealer to get fixed.