interesting that I just read your post and then @AliceLily in this order.Severely affected and difficult to say tbh because not very physically active, I’d say no. Maybe if I was more active? Maybe ‘it’s complicated’ would be better as an answer. But it’s not something I’d say is noticeable or limiting currently. There’s can be a sort of pain or tightness perhaps, but it doesn’t feel like the muscular stiffness you describe. And definitely no new/different cracking or stiff joints as described.
If was thinking of what came first since I first had ME (I remember overly sore legs, particularly calves but it affecting my gait partly because of this and the tendency to combine determination to still try and walk as fast with being exhausted) and specifically about stiffness then the hands stand out and wasn't due to anything like age or deconditioning. I'd and still am always trying to stretch them out like they are stiff and feel like they are stuck and should be able to span further than they can. In the recent year, which is decades in, I can sometimes actually finally get the odd click/clunk on my thumb or a finger and that doesn't relieve it but feels a joy when it happens.
And I'd get a clicking uncomfortable wrist particularly if I'd been using eg my laptop a lot.