They call her ugly cuz the plot needs it to happen.
That being said, this one is just another generic isekai. Nothing too special it seems. The male chars are lean towards the very feminine looking side though. Little too much so imo.
I Woke Up as the Ugly Duckling/I Became the Ugly Lady the title seems to be missing the "just for 1 day" part
Also, why is there no yuri tag? The ML is borderline women lol
Something about the art style makes all the characters look like lizards from Rango to me. It's like the other stories with this exact plot, except worse lol.
instant transformation plot, i thougth this manhwa developmet is like "i'll save this damn family", at least they should show us how she struggle with her chubby body for 10+ or 20+ chapter, but nope, the author scrap that self improve development plot and go with instant mumbo jumbo transformation from ugly duckling to beautifull swan