ΔE 16.5, loose: different enough that you should pick on purpose. Ungor Flesh is a little darker, much more muted, warmer than Plague Yellow.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Ungor Flesh is a little darker, much more muted, warmer than Plague Yellow.
The same difference applies the other way round: Plague Yellow is a little lighter, much more saturated, cooler.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Plague Yellow on the colour wheel See Ungor Flesh on the colour wheel
All matches: Plague Yellow equivalents · Ungor Flesh equivalents