ld-elf.so.1: Shared object "libcrypto.so.8" not found, required by "mumble"
Even after full rebuild, also the port is not available through pkg.
This sounds to me like a broken OS install/upgrade. Were you moving from FreeBSD 11 to 12 by chance? libcrypto.so.8 is part of the base OS in FreeBSD 11. It seems to me like you were running FreeBSD 11 packages on a FreeBSD 12 install to get that error, or something similar to it.
If you were truly missing libcrypto.so.8 a lot of software would not work.