Why would you explain this with a conspiracy theory of collusion instead of Occam's razor -- that they were responding to similar changes in market conditions, with input from similar shareholders?

This is not a conspiracy theory, even though what I'm about to say will sound like it. If you can talk to someone from the exec class in confidence (which unfortunately may require a close personal relationship or high trust), they'll tell you there was a clear -- if somewhat tacit -- understanding that the job market had gotten too hot during Covid and something "had to be done" about it after ZIRP ended.

Elon's layoffs at Twitter were basically the signal for the rest of the industry that it's time to reverse the trend.

occam isn’t a law of nature, it’s an expression or a sharp quip

I don’t see a conspiracy here other than sheep herd mentality of hire hire hire then too many

Please stop validating the language of the oppressors