I’ve lived under UN sanctions imposed on Serbia under Milosevic regime during the nineties. Two things happen: 1) people in the regime leadership don’t suffer 2) the little people who do suffer feel attacked and rally around the leader. Pretty much the opposite of what the sanctions ostensibly aim to achieve.
This same dynamic played out in Cuba, North Korea, Iran, you name it, for decades with no good effect.
What brought Milosevic regime down was the aerial NATO assault and its aftermath, not the sanctions.
As far as I can tell sanctions are a way for US politicians (they may be imposed by all the western countries, but I can’t think of an example where US wasn’t the leader) to look like they are punishing the offending country without going to war. They just don’t seem to work.