My previous PM was ultra valuable. Put devs in contact with the customers, got out of the way of deciding what to build, and then sheltered the devs from the chaos of customers. He was also smart about what could be done and in what timeline, always working from the estimates engineers gave, working backwards and deciding what scope could be cut and where, who if another team could loan us people. He was the right balance of umbrella, partner and pass through. It was magnificent.
My company, being more than a little bit toxic, he got transferred to a new manager who took an instant dislike to him and he was pulled off all his projects and then fired for not delivering anything. (bit of an exaggeration, he got put onto one of those "all responsibility, no authority" type projects where he was responsible for making sure everyone at the company stopped using the VPN, but he had no authority to force teams to build or migrate services to be available outside the VPN, and there were 2+ decades of services to migrate, and he couldn't direct people to stop connecting to VPN if they needed something that was inside the VPN)
The PM that came along to replace him described himself to all the engineers as "the next Elon", wouldn't let engineers talk to customers, personally decided what features to build with no input from the dev team, even when making technically difficult decisions. He asked for estimates from devs but never used them. Often giving us both half the time asked for, and half the engineers asked for to deliver a project. He never deflected chaos from customers, just added a translation layer that made it impossible to make the customers happy. Everything was an emergency, every feature necessary for an MVP. He'd constantly harass people for status updates, forget what they were working on and harass them again. He constantly asked for documents to be written for himself that he never bothered to open the links too.
He was actively toxic, wrong and an impediment.
He'd send out launch announcements to the org celebrating the projects that were completed and it was customary to list key people who delivered the project. He'd forget whole teams of people that worked on the project. One time he left me off of a project that I lead, got everyone in our sibling team that was helping out though. One person he never forgot to list as being a key person involved in the project was himself. Even in projects he had never heard of before having to write the launch announcement.
That behavior was rewarded, for whatever reason. Although he finally left the company when one of the many rounds of "you must work from the same office as your manager" bullshit caught him up and he wouldn't relocate from canada to the US.