"A feature not making it into a sprint" is your problem. You will get in trouble for that, it will make you look bad in front of your boss, etc. "Not following best practices" is not your problem. If the code turns into a mess, it's not you who will have to deal with the consequences, at least not you directly. As a manager you will demand that your senior developers fix that (while still shipping features, of course). After all, that's what expected of senior developers. So, the incentives for you and for your senior engineers are not aligned.
Of course I don't know if that's even remotely close to your reasoning. I don't know you or your project or your priorities, I have no idea what "best practices" we're talking about and how reasonable it is to follow or not follow them in a given situation. I might be totally wrong, you may have all the right reasons to be mad about those reviews. But the comment makes it sound like your senior engineers are idiots who block PRs for no reason, and that can't be good for your team.