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

Calculating dependencies ... done!
Dependency resolution took 1.05 s (backtrack: 0/20).

[ebuild  N     ] app-arch/lz4-1.10.0-r1:0/1.10.0-meson::gentoo  USE="-static-libs -test" 379 KiB
[ebuild  N     ] dev-libs/librdkafka-2.10.0:0/1::gentoo  USE="lz4 ssl zstd -sasl -static-libs" 4703 KiB

Total: 2 packages (2 new), Size of downloads: 5081 KiB