I'm sorry, I just cannot wrap my brain around the fact that you're complaining about the fact that you have to hit a button 1 extra time like I just had to do it for this post and my world remained unchanged. However I cannot say what is and what is not a problem to you
But, it's not consistent. It only happens in Safari. Literally ALL other apps are unaffected and you can type as normal. As others said, it's programmed into our muscle memory to hit a comma, then space, then keep typing.
Now, it looks something like "It's programmed into our muscle memory to hit a comma, 35-(6#$@" until you realize you've been hitting the wrong keys and you have to delete everything you said after the comma, hit the ABC button again and finish typing what should've already been there.