Her movie was trashing but her show was great. both flopped regardless of quality because there isn't an audience for Ms Marvel.
MCU main mistake is thinking any and every marvel character has franchise appeal. Treating virtual unknowns with the same reference (or even more in some case) than well established characters. They are 13 years deep into the MCU not a single Blade movie which would be a guaranteed hit, But a Ms Marvel Series and movie? Thats the problem.
Even the movies in this phase that have been mid. People will enjoy a mid A lister, over an S tier unknown is most cases.
They think because they made guardians work they can do anything. But if anything that is seeming like a fluke now.