OpenSSL 3.0.x (3.0.9 and 3.0.10) seems to be marked as stable on my amd64 system, and 1.0.x is masked:

  $ eix -I dev-libs/openssl | grep -e 'Available versions:'
       Available versions:  [M]1.0.2u-r1^td [M]1.1.1u(0/1.1)^t [M](~)1.1.1v(0/1.1)^t 3.0.9-r1(0/3)^t 3.0.9-r2(0/3)^t 3.0.10(0/3)^t (~)3.1.1-r1(0/3)^t (~)3.1.1-r2(0/3)^t (~)3.1.2(0/3)^t {+asm bindist fips gmp kerberos ktls rfc3779 sctp sslv2 (+)sslv3 static-libs test tls-compression (+)tls-heartbeat vanilla verify-sig weak-ssl-ciphers ABI_MIPS="n32 n64 o32" ABI_S390="32 64" ABI_X86="32 64 x32" CPU_FLAGS_X86="sse2"}

3.0.x is even stable on my ppc64le system, didn't even notice the upgrade.

It's definitely marked as stable, everything else is masked.