When you have QA with AMS machines enabled and Deadlock's Stacking Beltboxes & Compact Loaders mod together QA adds an AMS version of the Stacking Beltbox which just stacks and unstacks items. So when you add 2 quality modules to it you can create stacking/unstacking chains that turn all materials into quality ones.
It seemed very unbalanced to me so im reporting it here in case you want to exclude the stacking beltboxes from the AMS machines.

I'm still waiting on a response from the author to my PR here:
https://github.com/shanemadden/factorio-deadlock-beltboxes-loaders/pull/42
From the looks of it, the mod author isn't active anymore and the mod is dead, but it's hard to say for sure.

There also isn't an easy way to fix it in QA as there's no way to get all the beltboxes the mod adds. Either way, we'd need some changes on the mod itself for that to happen.