Try asking on https://github.com/saulpw/visidata https://github.com/saulpw/visidata the community there can help. I am seeing this issue on a Mac with ghostty

Try asking on https://github.com/saulpw/visidata https://github.com/saulpw/visidata the community there can help. I am seeing this issue on a Mac with ghostty but not with wezterm, from the same binary. Ghostty shows some correct characters and some diamond-question marks, and a line usually contains one or the other. The ghostty inspector shows the diamonds are not the blocks.