Sometimes CudaText wants to connect to internet, on start up usually, and finally I decided to see why what exactly it is it wants to do. Apparently it connects to smart-ip.net, I pasted details here: https://pastebin.com/3Je4rJJ2 .
But why, it is because of some plugin?
Not download, but upload. Also to smart-ip.net, and not Github.
I downloaded another portable CudaText, download no plugins, and restart, and it does not connect to the internet. With my actual CudaText installation it is reproducible.
I did the obvious thing (what I should have thought of first ) and searched for smart-ip, and found it in \cudatext-win-x64-1.87.0.0\py\cuda_ip_address_helper\__init__.py .