There are plenty of synonyms for the phrase "more mortifying" that can help to convey a sense of extreme embarrassment or shame. Some possible alternatives might include "more humiliating," "more embarrassing," "more shameful," "more degrading," or "more demeaning." Each of these phrases can effectively capture the feelings of discomfort that come with being publicly humiliated or embarrassed, whether by an unfortunate mistake or through the actions of others. Additionally, they can be used in a wide range of contexts, from personal stories to news articles to social media posts, to convey a sense of intense emotion and vulnerability.