This is hard to gauge though because it's rarely only a change from 1080p to 4k. The screen tech often changes from LCD to LED (or microLED, or OLED), there's a

This is hard to gauge though because it's rarely only a change from 1080p to 4k. The screen tech often changes from LCD to LED (or microLED, or OLED), there's all manner of motion smoothing added, sometimes higher refresh rates, and so on. Anecdotally I was at a family Christmas where relatives were watching some home videos that were encoded at 480p on a flash drive on a new TV, and they all said that the quality of the 4K picture was amazing despite the fact they were all watching 480P video (without upscaling because I'd turned it off.) To be fair it did look better than an old TV, but not because of the resolution.