>>419548209
You can blame bad shaders like UTS and liltoon for that one.
World brightness should always be tested around Standard, but the "looking flat" thing that the other anon was talking about is basically just the fault of Standard for having half its features not be usable without a realtime light.
Then again, being able to guess the baked light direction is kind-of black magic to shader authors and is not widely known about outside of the VRChat ecosystem, so I don't necessarily fault them for it.