Pallette colors are rendered differently on 2 versions

[Taw Tano]

I use terminator on Xubuntu 18.04 with the default "Ambient" pallette. (terminator version 1.91)
When I updated to Xubuntu 20.04 (sorry I don't know the terminator version there ), it seems that the default "Ambient" pallette remained, but the colors are rendered a lot darker and a bit uglier.

If I try to modify these colors to more lighter ones, then the midnight commander background color is shown too light and I cannot distinguish the text.

I attached the 2 pics (lighter - 18.04, darker - 20.04)

thanks