https://screenrant.com/conners-season-5-dan-louise-death-roseanne-tragedy-plot-why/

The Conners season 5 used the show's annual Christmas episode to casually reveal that one forgotten Roseanne character tragically died offscreen.

I suppose since the two actresses who played the role, Ann Wedgeworth and Debbie Reynolds have both passed away, it was the only route to go in order to aknowledge the character's death.