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

Calculating dependencies ... done!
Dependency resolution took 3.54 s (backtrack: 5/20).

[ebuild  r  UD ] dev-libs/libunistring-1.0:0/2::gentoo [1.3:0/5::gentoo] USE="-doc -static-libs" 2313 KiB
[ebuild  rR    ] net-dns/libidn2-2.3.8:0/2::gentoo  USE="nls -static-libs -verify-sig" 2183 KiB
[ebuild  r  U  ] net-libs/gnutls-3.8.13:0/30.30::gentoo [3.8.12-r1:0/30.30::gentoo] USE="cxx idn nls openssl pkcs11 post-quantum tls-heartbeat zlib -brotli -dane -doc -examples -sslv2 -sslv3 -static-libs -systemtap -test -test-full -tools -verify-sig -zstd" 7105 KiB
[ebuild  r  U  ] net-libs/libpsl-0.23.3::gentoo [0.21.5::gentoo] USE="idn -icu -static-libs -test" 7648 KiB

Total: 4 packages (2 upgrades, 1 downgrade, 1 reinstall), Size of downloads: 19247 KiB

WARNING: One or more updates/rebuilds have been skipped due to a dependency conflict:

dev-libs/libunistring:0

  (dev-libs/libunistring-1.4.2:0/5::gentoo, ebuild scheduled for merge) USE="-doc -static-libs" conflicts with
    =dev-libs/libunistring-1.0


The following packages are causing rebuilds:

  (dev-libs/libunistring-1.0:0/2::gentoo, ebuild scheduled for merge) causes rebuilds for:
    (net-libs/gnutls-3.8.13:0/30.30::gentoo, ebuild scheduled for merge)
    (net-dns/libidn2-2.3.8:0/2::gentoo, ebuild scheduled for merge)
    (net-libs/libpsl-0.23.3:0/0::gentoo, ebuild scheduled for merge)