All companies will have QC issues, the good companies make it as painless as possible to fix those issues
And then there is OOUK who deny all knowledge
I’m not so much asking about quality control as much the General quality. It’s like comparing ZWO narrowband filters against those of Astrodon. ZWOs are significantly cheaper but with that come wth some quirks that you can let bother you or not.
QHY make a M54 to Nikon F Mount adapter which I think is quite reasonable. FLI make one for their CFWs. As Suavi points out, there may be design differences like better shielding or stiffer heavier materials.
The reason I brought up FLI cameras is that if you compare the PL16803 against that made from SBIG, QHY, SX (I think they do one) and Moravian. The FLI costs a lot more but you get 10-15°C deeper cooling, faster download speeds, Argon purged chambers and better read noise (6-7 e- vs 10-12 e-). You pay extra but you do get that extra in performance. Same went for Astrodon narrowband filters, they cost more but generally have less scatters than the cheaper competitors.