I have the same issue on Windows with WezTerm Nightly. Running the following command in PowerShell (pwsh in WezTerm and Windows Terminal) outputs the appropriate underlines:
``` Write-Host "`e[58:2::255:0:0m`e[4:1msingle`e[4:2mdouble`e[4:3mcurly`e[4:4mdotted`e[4:5mdashed`e[0m" ``` [image: Screenshot 2026-01-13 164535.png] However, Vim 9.1 completely freaks out -- -- You received this message from the "vim_dev" maillist. Do not top-post! Type your reply below the text you are replying to. For more information, visit http://www.vim.org/maillist.php --- You received this message because you are subscribed to the Google Groups "vim_dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/vim_dev/76a65775-8106-4354-8dc0-dadf0756b3adn%40googlegroups.com.
