Discord desktop on this machine self-updates into ~/.config/discord (pacman package is only a bootstrap; its version lags, which is normal). It can freeze forever on the “Discord Updater” splash at 90%.
Diagnosis: installs/downloads both report 10/10 but progress stays 90; updater threads sit idle in futex/epoll; a 0-byte file in ~/.config/discord/download/incoming/.tmp* opened at the stall time is the dead download; the last module (e.g. discord_spellcheck) never appears in .app-
Fix: kill the whole Discord tree (bwrap launcher + splash), delete ~/.config/discord/.app-