It's hard to say without seeing the wheel or having an actual tension measurement other than some spokes feel loose. One thing you should be aware of is that on rear wheels the left side spokes usually have only about 60% of the tension of the right.

At issue is the overall tension, the evenness of tension on either flange and whether the wheel runs true , both side to side and radially (hops and dips) and is centered on the hub (dish).

It's hard to give you a decent guide to how loose is too loose on the left, or how tight is too tight on the right, but you might feel other wheels to get a sense of it. If you have uneven tension on either side, especially when crossed spokes are mis-matched, you might try to transfer some load from one to the other, but be aware that sometimes the rim itself is bent, and some unevenness is the result of the spokes forcing it back to line.