This is 100% down to me trying to run Rack on Centos7, which is not optimal for an audio workstation, but.
It has to do with how the SO file is linked on Linux. This comes up from time to time with different plugins.
[1.467 warn src/plugin.cpp:90] Failed to load library /home/kwilliams/.Rack/plugins/VCV-Host/plugin.so: /lib64/libm.so.6: version `GLIBC_2.27’ not found (required by /home/kwilliams/.Rack/plugins/VCV-Host/plugin.so)