Base2Tone_MorningLight has yellow background
When I use Base2Tone_MorningLight, I get a yellow background.

Vim version: https://pastebin.com/raw/W3MUDi79 iTerm2 version: 3.4.12
@tactlessfish Thanks for the feedback. I can confirm this issue in this configuration with the default Vim (that comes with Mac M1 on Big Sur) on this latest version of iTerm2. It seems to fallback on the 256 terminal colors ISO the true colors in this setup. No such problem with NeoVim on the same machine (Mac M1 on Big Sur) with that same latest version of iTerm2 though, works fine. Also works fine with Vim on Mac OSX on iTerm2 version: 3.3.12 So I'm going to think about this a bit more, and I know it's not trivial to update the default Vim that comes with MacOS, and I don't even know if this would fix this issue. The only thing I can recommend for now is to switch over to Neovim.
Ah, I see. Thanks for the information!
For anyone that finds this issue, switching to the nixpkgs version of vim and setting termguicolors is another option.