notcurses 3.0.4+dfsg.1-1 ought be migrating to testing soon, and if there is any love in this world, it will resolve the continued failures. the most recent i see is from today, still using notcurses 3.0.3.
i added several similar unit tests to the notcurses suite, and managed to reproduce the lockup in at least one of its incarnations. we'll see.