Thank you Salman.
I agree that the new way to read back makes manual typing on the top row a little less forgiving, in that the top row is now only as forgiving as the other two rows. Before, the top row was more forgiving on the Y axis since you could be touching as high up as possible and still get a top row letter. In effect, the top row extended all the way to the top of the screen, in contrast to the two bottom rows. But I still think such a change might be beneficial overall, if we consider the benefits. Consider a related example, where we might add an option for a number row or commonly used symbols row above the QWERTY row. If and when we do that, the top row would need to be limited in height and reduced to be just as forgiving as all other rows, like it is right now in this new build.
Also note that this is technically not a new gesture in the entire system, but rather an extension of the existing long press gesture. The way I thought about it, is that all that space at the top is wasted when you are typing manually, and could be used for something more useful. It's now as if a new button was added on top of the QWERTY row than spans the entire keyboard width, and its label is always set to be your current text. And not being a new gesture also means that you shouldn't need to be any more careful or otherwise change how or where you performed the dismiss or next keyboard gestures - it should all be identical as before unless I botched something.
It's also important to note that the overall explore gesture we've always had is in a way already interfering with the dismiss or next keyboard gestures, in that you might sometimes get a manual letter entered instead of exiting the keyboard, or vice-versa. The difference now is that you might get your text read back to you instead of the manual letter, which also seems to be a more forgiving mistake, since at least you don't end up with a dangling extra letter somewhere. So if you had performed the exact same finger movements that you did just now, but on a previous build, you'd still have the same success when trying to switch to the iOS keyboard as well as delete the unwanted single character.
I'm open to hearing more about everyone's experience and thoughts about this, after giving it a few tries to adjust to the change.