She's just not comfortable in public speaking. She gets nervous and over-compensates in this manner.
I was in toastmasters and saw this a lot with new speakers and with some who just aren't comfortable in front of others.
I do think she realizes she's in over her head and the nervousness from that causes her to over compensate when speaking.
Good take Re public speaking. She’s used to reading scripts and delivering catchy pre rehearsed phrases. Most in controlled settings
Probably sees the audience reacting to her weirdness and thinks she can do her ditz rountine.and get by with it.