Earlier quoted context omitted.
I have seen precisely zero consequences for these people because they usually leave after not too long and go somewhere else, sometimes for higher pay. The slower folks end up getting the worse code and no raises in exchange for comradery. But also I have no idea how that situation arises unless the slower folks are just auto-approving PRs. You kind of did that to yourself if you let the new person get away with it.
I can tell you how that situation comes about. You start by rejecting those PRs, saying "write more maintainable code, not quick hacks". Management starts pressuring the original developer "why is it not merged yet, I thought you had it working". That developer hits back with "well, it failed code review, they want me to refactor it". Management goes back to the reviewer, "why did you fail this? It meets coding stand…
IME the manager just approves the PR themself to "bias for action", someone else will pick up the pieces