This is my first use of Lcnc and I was trying to install qtpyvcp and Probe Basic, but over the past couple of months the switch to python3 has caused many issues.
As far as I understand (not much) the development version of qtpyvcp needs lcnc 2.9 RIP installation. And recently some very kind people have posted mostly idiot-proof instructions on how to get Lcnc 2.9 RIP with qtpyvcp & PB installed under MX Linux 21.
So, in short - I don't know why I need RIP, but I followed the directions and it's working.