For some reason, most of these (and other narration AIs) sound like someone reading off a teleprompter, rather than natural speaking voices. I'm not sure what exactly it is, but I'm left feeling like the speaker isn't really sure of what the next words are, and the stresses between the words are all over the place. It's like the emphasis over a sentence doesn't really match how humans sound.
Still a bit teleprompter-ish but there are tools to go in and adjust pace and style throughout and you probably hear a lot of stuff with people not using those creative features. 11labs might very well be one of the best bits of software I've used, it's a great deal of fun to play with and if you're willing to spend the time the results are superb - I don't even have a use case, I just like making them because they're fun to listen to, ha!