I very recently joined a new large multi-disciplinary engineering team after running my own product-engineering org as a single-threaded leader for a few years

I very recently joined a new large multi-disciplinary engineering team after running my own product-engineering org as a single-threaded leader for a few years in a related field. I'm absolutely shocked by the product-engineering dynamic here; PMs pull a date from thin air as you say, plop it in a document, and then bypass TPMs and engineering managers and take it straight to their favorite engineer to have the work started mid-Sprint. I can't wait to fix this mess. PMs should never put down any date themselves unless the task has 0 engineering dependencies.