Massive 4K UHD Replication QC issue?

[WBMakeVMarsMovieNOW]

A few notes:

I had some discs, blu-ray and UHD that had bad sectors. I thought maybe it some cases my PC drive was just finicky, but then the motor died and with the new PC drive I see that it finds the exact same sectors bad on the exact same discs so I think the disc errors I had were flat out disc issues.

It does seem like discs are somewhat more likely to have errors over the last few years than earlier on (aside from known problem discs of the earliest era where some get that rot).

My first copy of Zach Snyder's Justice League had disc 1 of the UHD a total mess, riddled with more disc errors than I have ever encountered before by far. The replacement set's UHD disc 1 had zero disc errors and worked and verified just fine.

I find that DVDs can look a mess and still work fine with zero sector errors. Blu-ray, if they look a total mess, might have sector errors. UHD the slightest fingerprint or even just remnants of some sort of invisiable coating left over from manufacturing not washed off with detergent can sometimes give them a few errors that 100% disappear after cleaning.

Very minor hairline scratches I don't find cause many errors at all whether it is DVD, blu-ray or UHD. I've seen some horrendous looking rental sourced DVDs with nonethless zero sector errors or playback issues (although a few of those total messes do have problems). DVD do scratch much more easily than blu-ray or UHD. Some go nuts over finding a tiny hairline on a UHD and return it, etc. but I really don't find that tends to cause any sector errors when PC verifying a disc. In fact so far I've had zero instances where a bad UHD was because of that. All my bad UHD have either looked 100% utterly pristine (and simply had a pressing error) or have an small thin line in an arc that maybe looks like a scratch but is some sort of mini bubble or defect in layer bonding or something (I've had a few with these and I believe all but one had sector errors, maybe all). I have yet to have a scratch of any sort actually cause any UHD errors so far (I also haven't seen many scratches). I wouldn't be paranoid about a UHD loose in case new and returning them. These discs are harder than anything in the case and so should not scratch and even if they somehow did I believe it's only super rarely ever a problem. The real issues are badly pressed discs and surface bonding manufacturing defects. You could end up returning perfectly working discs for bum ones.

I seem to find European market UHD are a lot more prone to thrash my drive and a bit more prone to have reading issues than US market UHD overall so far.