Kind of a shot in the dark but it could be related to HDR? I had a monitor for a while that would render non-HDR content (like my desktop) too dark to use. Idk how you are watching but if you have the option for HDR in your TV or Monitor settings try disabling it. Every hardware display is a special hell to intact with for which I apologize in advance that I'm pointing you towards that.

Unless you have a really really nice display you probably won't care disabling it (a really really nice display I'll define a one that is certified to VESA DisplayHDR HDR400 or higher. annoyingly these have nothing to do with "HDR10", which basically means does more than no HDR. I'm hand waving a lot here, it's not the point)

now if you are on a computer you might have luck by setting the correct color profile and you can find some online (they usually have .icc as the extension) but you could also go through all the trouble and have the same result and things like macbooks will already have this set up correctly for the built in panel.

i had too much coffee today and Supergirl is a fun watch, it's not high art but i don't reallywant it to be so