I am not sure if this is a bug intended behaviour.
There some videos that have a passthrough tag but also have a normal background. I mean those videos where the background isn't green screen or something like this.
This video for example: https://www.sexlikereal.com/scenes/big-tits-doc-gets-creampied-38201
IMO these video should be also watchable without the passthrough enabled.
If you play the video in Google Chrome you get a setting applied that kinda makes it unwatchable. Can this be fixed?
EDIT: It's not the file that look like this. If you download the video an open it in VLC Media Player everything looks normal.