You need to make it pull from Wikipedia or some other semi-moderated source, else your Random button is going to turn into Microsoft's Tay real quick. I also notice your Professor voice is pretty clearly Jordan Peterson, which some people may have a problem with.
Also - if you are storing previous inputs (for any purpose) I’d let people know upfront!
I would maybe have a list of paragraphs from a few select public domain works in there, instead of using unfiltered user input.
If you're looking to position yourself as an inclusive company, don't regurgitate text put in by previous users. Because idiots on the internet will idiot. And that idiocy now is cosigned with your company name and logo.
People have been putting stupid stuff into text-to-speech since the early 80s after it was popularised by the SP0256 chip.