From my experience with multiple companies that have suffered big declines, designers leaving or getting laid off has been a reliable canary in the coal mine signal.
I don't know what is driving this current trend though. Apart from the bug tech giants giving up on their actual products and just focusing on stock prices?
Basically, product managers are a form of middle management. Good ones are indeed really valuable to have around. But not all of them are that good. And I've had the "pleasure" of working with a few spectacularly ineffective ones as well as a few really good ones. Same with designers. I've worked with some fantastic designers over the years that I would recommend to anyone. But also a few not so great ones. Some companies actually think of designers almost as something they can just parachute in as a generic skill. I think that's a mistake generally but it is what it is at many companies. Good design however is usually the work of a few people and not a lot of them.
When you look at cost and you need to cut some, you prioritize by what people add to the equation. So, it's not surprising that say a lot of maybe relatively junior product managers or designers aren't really considered that essential relative to engineers that actually can fix bugs, add features, and keep things going without either of those type of people involved. Of course there's a point where teams become dysfunctional. But there's a sweet spot in between where they might become more effective.
In VC funded teams with a track record of hiring people as fast as they can, most of them can loose a lot of people before they ever reach that sweet spot. I'd argue most of the FANG companies could do a lot better than they do right now with far less people. Throwing more people at a thing doesn't make things better. Fred Brooks (recently deceased) figured that out decades ago. That hasn't really changed. The inverse is also true maybe (removing people from large teams undoes the damage that you did by hiring them).
I have seen this happen many times ... I've just never seen it change. And once I asked THE captain, and he was pretty sure he was going to increase rather than decrease project managers and lower the amount of engineers.
I mean, clearly this is exactly how companies like it. Many people discussing, with as little actual real information as possible, what to do. Then they use heavy-handed tactics attempting to enforce it.
90% of time this doesn't work, because while people bend (and break), reality neither bends nor breaks. A lot of stuff just can't be done.
This was invariably solved by increasing management and all the kinds of project/program/... managers. Usually the more successful ones among them were the ones that were better at lying to higher up management. (and yes, usually by "not lying", but by redefining the project until it was done "successfully", half the time by destroying the actual work done and declaring the situation before the project started as the success management wanted)
https://interviewing.io/blog/how-many-engineers-laid-off-in-...
I actually think the estimate there for "software engineers" is too high, because it's likely that a very large number of layoffs in "software engineering" was engineering management, especially middle management and director level roles. Meta was perhaps the most transparent about their desire for a flatter org structure.
Obviously this is not always the case (Amazon, for example, canned much of the Alexa devices division), but I think companies realized that in many cases there were "too many cooks in the kitchen".
Product and design hiring often coincide with a focus on growth. New features, new products, new product lines to grow the entire pie. Focusing on profitability can shift toward making existing products more efficient and streamlined, or just not changing them so much and finding ways to save on costs.