I don’t think their quality is slipping, I think their value is.
I’ve got a VX-III and it is still excellent, as is my VX3.
I had a VX3i and pushed it forward, I wasn’t big on the B&C reticle but bro was and it’s still working perfectly for him.
I also got a VX5 with the fire dot, it’s absolutely amazing and not issues with it.
Then I purchased a few new VX3HD’s with the CDS-ZL caps, one out of the box had a dint in the elevation cap and a questionable looking seal under it. Sent it for warranty and could not have received better service. Both have been perfect ever since.
So in my opinion what I’m getting is top notch.
But my ability to easily justify purchasing them is getting strained due to many causes not all their own.
When I look at what I paid for some of the older ones in comparison to the newer ones they really haven’t gone up all that much.
But my disposable income has been eroded by so many other things it feels like they have.
All that said I still haven’t found another brand I’d trust more to replace them when my only criteria for change is perceived value.
However YMMV,