I don't think the pressure is always, or even ever from the company to the open source maintainers. Instead it will be from the developers working for the company, who are asked to deliver their feature, and require improvements or new features from open source to help them do it. They will personally cut issues, possibly insist, be rude, and name call the project or maintainers when they can't get traction.

I think this might happen also from University students who are similarly stuck for a school project of some sort.

Mind you, most people don't do that, but it takes only a few bad apples.