There was a list floating around but its been a long time. Now days its very common to have fake 4k masters. https://www.digiraw.com/DVD-4K-Bluray-ripping-serv

There was a list floating around but its been a long time. Now days its very common to have fake 4k masters. https://www.digiraw.com/DVD-4K-Bluray-ripping-service/4K-UHD-ripping-service/the-real-or-fake-4K-list/ https://www.digiraw.com/DVD-4K-Bluray-ripping-service/4K-UHD... I don't think anyone upscaled a dvd recently for release on BR though, was mainly an issue right around when BR came out in the rush to get content out. Same with UHDs, today it shouldn't be as much of an issue.