So... here's the situation I find myself in.
Back when iPad OS 13 was still in beta, we're talking beta 1 here, I put my iPad 6th gen onto the program and almost immediately I started having problems with speech. Those problems lasted until the final release, and are even still present in iPad OS 13.1.3 (I haven't had the chance to update to 13.2 and won't until Friday, but I doubt that will fix it).
I got an iPhone XR in August and, upon upgrading to iOS 13 on that device, I started to experience this issue on it as well. My iPhone 6S, the older phone that I had previously, does the same.
However, I borrowed my father's phone at one point (also an iPhone 6S) and tested it to see if I would get the same issue.
I did not.
I also borrowed my mother's iPhone 7+ and again, there is no issue.
For reference, below I have attached a few instances of voiceover weirdness. The first one just happened randomly and I have never heard anything like it before, but the second one is pretty much constant.
What I've done in each case is have voiceover read the entire piece of text, and then I have gone through it word by word.
Also please note I have already tried to backup and restore from iCloud on my phone. That didn't fix it. Nor did the same from iTunes itself on my Windows PC.