These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 1.04 s (backtrack: 0/20).

[ebuild  N     ] dev-lang/yasm-1.3.0-r2::gentoo  USE="nls" 1458 KiB
[ebuild  N     ] media-libs/libaom-3.14.1:0/3::gentoo  USE="examples (-big-endian) -debug -doc -test" CPU_FLAGS_X86="avx avx2 mmx sse sse2 sse3 sse4_1 sse4_2 ssse3" 6220 KiB
[ebuild  N     ] media-libs/libavif-1.4.2:0/16.4::gentoo  USE="aom -dav1d -examples -extras -gdk-pixbuf -libyuv -rav1e -svt-av1 -test" 14323 KiB

Total: 3 packages (3 new), Size of downloads: 21999 KiB