Tech jobs are somewhat decoupled from true demand. They are usually inherently an indirect investment, not a direct cost. But when they and their activities go away, you lose the B2B demand that they had to accomplish their jobs and the B2C demand they had from spending their salaries.
For example, my last 3 product jobs have been a business travel offering, an HR learning management tool, and a Predictive analytics tool for data scientists working in marketing. A lot of the users who paid the bills were some form of tech worker that were executing on projects that were future investments.
Investors have been handed a truly mind-boggling amount of cash since 2008, but there hasn't been a lot of stimulus to the actual day-to-day economy. Valuations had to go up to accommodate this cash, and without a corresponding increase in consumer spending there's really only one lever in the financial model that drastically impacts valuation without seriously changing the core business: year-on-year growth.
Most growth stories are laughably improbable, and the investors need plausibility to play the game. Fundraising turned into a story-telling competition of who could spin the most plausible growth story that is hard to verify and hasn't been disproved. That story is some form of "we will completely dominate market X, by building software that enables hyper-scaling with minimal unit costs, and that also includes AI/ML/Optimization (to be developed) that solves the inherently hard problems in this industry."
That story is used for both VC-style external fundraising and internal project pitches, and it has crowded out most other approaches. A side-effect of that story has been a massive bubble in the jobs that can deliver on it - software engineers, designers, data scientists, product managers, etc. The game at most firms has been to keep kicking the outcomes down the road and claim that the hockey stick growth is right around the corner.
That worked until interest rates went up and far-future cash became much less valuable. The CFO and the Fund now need to show results in the very near term, and the knives are being sharpened for departments and companies who can't deliver on that. Those departments and companies remove demand when they fold, and there isn't a clear immediate activity that returns quick cash to replace them.