These don't seem the same at all frankly, the unity thing seems like a blatant attempt at rent extraction. Gamepass is at least offering a genuine service in its role as middleman.
Gamepass is literally renting games on a flat monthly fee (which they've recently increased, btw). Unity chose a really stupid approach to handle their new pricing, but they're doing what everyone is doing, hiking prices in an uncertain market. I suspect this is at least partially because of services like Gamepass, but I'd love to know more.
Unity is trying to redefine their existing product as a service. This isn't exactly 'just' a price hike and I think its why people are so upset about it.
And I agree with your suspicion. It seems that finding a way to offer a service instead of a product is a license to print money, so I imagine many companies have people pushing for this regardless of how well it would be received or how much sense it makes.
Unity has ~7,000 employees, and is losing money. They need to a way to monetize, and they are clumsily trying to target their most successful users to pay more. Price increase aren't rent seeking.