Mesh shows 1:1 scaled textures of the base material instead of scaled overrides. The same link of the same object always has the same problem regardless of relogging or teleporting in and out. When the amount of overrides in the area was reduced by the landowner, the problem slowly started going away in general. I had packet drops of 0.1 to 0.2%.

Can't get other people to reproduce it. It has worked as expected for 5-10 people I've asked. They had hardware older and newer as well as higher and lower end compared to mine. For me I just have to visit a particular place in a particular sim and every object has the same issue permanently regardless of teleporting in and out or relogging.

Logging in and out or teleporting away and back rules out random packet drops. Clearing cache, testing both on Firestorm and fresh Second Life Viewer, defaulting graphics and debug settings should rule out viewer-based issues. Updating GPU drivers and having the same problem on 2 different machines, where one was also a fresh install, should rule out hardware issues. Friends having lower and higher end as well as older and newer hardware should rule out hardware compatibility issues. Checking with an alt should rule account-based issues. Checking in separate geographical locations should rule out local network issues. Other people seeing it correctly should rule out server issues? Overrides were used in a very large number due to using them in place of making new materials for static objects. When the amount of overrides were reduced in the area, even things that were still overridden, but had been faulty before, started looking correct. I've not managed to get other people in my larger geographical region to try it other then myself 300km away still having the same issue. But people in nearby states/countries are seeing it correctly, leading me to believe it's localized to my greater area.

Talking with a friend who is building their own viewer, I believe that the issue might be with how override packets are sent and that some routers on the way to me may block or drop the packets due to size or frequency or some other factor, in a consistent way. When the amount of overrides dropped, the amount or size of the packets drop with it and then may be passed through. With everything that is hopefully correctly ruled out, there aren't much else that could be the issue I think. I also have no idea how it could be consistently tested by testers or developers since it seems to be a geographically localized issue.