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

Calculating dependencies ... done!
Dependency resolution took 1.70 s (backtrack: 0/20).

[ebuild  N     ] acct-group/tss-0-r3::gentoo  0 KiB
[ebuild  N     ] acct-user/tss-0-r3::gentoo  0 KiB
[ebuild     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 tools* zlib -brotli -dane -doc -examples -sslv2 -sslv3 -static-libs -systemtap -test -test-full -verify-sig -zstd" 7105 KiB
[ebuild  N     ] dev-libs/libtpms-0.10.2::gentoo  1367 KiB
[ebuild  N     ] dev-libs/json-glib-1.10.8::gentoo  USE="nls -gtk-doc -introspection -test" 1264 KiB
[ebuild  N     ] app-crypt/swtpm-0.10.1::gentoo  USE="seccomp -fuse -test" 407 KiB

Total: 6 packages (1 upgrade, 5 new), Size of downloads: 10142 KiB

The following USE changes are necessary to proceed:
 (see "package.use" in the portage(5) man page for more details)
# required by app-crypt/swtpm-0.10.1::gentoo
# required by =app-crypt/swtpm-0.10.1 (argument)
>=net-libs/gnutls-3.8.13 tools